copied from ../2016-11-30-Profitbricks without any changes yet

Signed-off-by: Holger Levsen <holger@layer-acht.org>

1 files changed, 4677 insertions, 0 deletions

diff --git a/userContent/presentations/2017-08-07-DebConf17/js/reveal.js b/userContent/presentations/2017-08-07-DebConf17/js/reveal.js
new file mode 100644
index 00000000..2c929545
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+++ b/userContent/presentations/2017-08-07-DebConf17/js/reveal.js
@@ -0,0 +1,4677 @@
+/*!
+ * reveal.js
+ * http://lab.hakim.se/reveal-js
+ * MIT licensed
+ *
+ * Copyright (C) 2016 Hakim El Hattab, http://hakim.se
+ */
+(function( root, factory ) {
+	if( typeof define === 'function' && define.amd ) {
+		// AMD. Register as an anonymous module.
+		define( function() {
+			root.Reveal = factory();
+			return root.Reveal;
+		} );
+	} else if( typeof exports === 'object' ) {
+		// Node. Does not work with strict CommonJS.
+		module.exports = factory();
+	} else {
+		// Browser globals.
+		root.Reveal = factory();
+	}
+}( this, function() {
+
+	'use strict';
+
+	var Reveal;
+
+	var SLIDES_SELECTOR = '.slides section',
+		HORIZONTAL_SLIDES_SELECTOR = '.slides>section',
+		VERTICAL_SLIDES_SELECTOR = '.slides>section.present>section',
+		HOME_SLIDE_SELECTOR = '.slides>section:first-of-type',
+
+		// Configuration defaults, can be overridden at initialization time
+		config = {
+
+			// The "normal" size of the presentation, aspect ratio will be preserved
+			// when the presentation is scaled to fit different resolutions
+			width: 960,
+			height: 700,
+
+			// Factor of the display size that should remain empty around the content
+			margin: 0.1,
+
+			// Bounds for smallest/largest possible scale to apply to content
+			minScale: 0.2,
+			maxScale: 1.5,
+
+			// Display controls in the bottom right corner
+			controls: true,
+
+			// Display a presentation progress bar
+			progress: true,
+
+			// Display the page number of the current slide
+			slideNumber: false,
+
+			// Push each slide change to the browser history
+			history: false,
+
+			// Enable keyboard shortcuts for navigation
+			keyboard: true,
+
+			// Optional function that blocks keyboard events when retuning false
+			keyboardCondition: null,
+
+			// Enable the slide overview mode
+			overview: true,
+
+			// Vertical centering of slides
+			center: true,
+
+			// Enables touch navigation on devices with touch input
+			touch: true,
+
+			// Loop the presentation
+			loop: false,
+
+			// Change the presentation direction to be RTL
+			rtl: false,
+
+			// Turns fragments on and off globally
+			fragments: true,
+
+			// Flags if the presentation is running in an embedded mode,
+			// i.e. contained within a limited portion of the screen
+			embedded: false,
+
+			// Flags if we should show a help overlay when the questionmark
+			// key is pressed
+			help: true,
+
+			// Flags if it should be possible to pause the presentation (blackout)
+			pause: true,
+
+			// Flags if speaker notes should be visible to all viewers
+			showNotes: false,
+
+			// Number of milliseconds between automatically proceeding to the
+			// next slide, disabled when set to 0, this value can be overwritten
+			// by using a data-autoslide attribute on your slides
+			autoSlide: 0,
+
+			// Stop auto-sliding after user input
+			autoSlideStoppable: true,
+
+			// Enable slide navigation via mouse wheel
+			mouseWheel: false,
+
+			// Apply a 3D roll to links on hover
+			rollingLinks: false,
+
+			// Hides the address bar on mobile devices
+			hideAddressBar: true,
+
+			// Opens links in an iframe preview overlay
+			previewLinks: false,
+
+			// Exposes the reveal.js API through window.postMessage
+			postMessage: true,
+
+			// Dispatches all reveal.js events to the parent window through postMessage
+			postMessageEvents: false,
+
+			// Focuses body when page changes visiblity to ensure keyboard shortcuts work
+			focusBodyOnPageVisibilityChange: true,
+
+			// Transition style
+			transition: 'slide', // none/fade/slide/convex/concave/zoom
+
+			// Transition speed
+			transitionSpeed: 'default', // default/fast/slow
+
+			// Transition style for full page slide backgrounds
+			backgroundTransition: 'fade', // none/fade/slide/convex/concave/zoom
+
+			// Parallax background image
+			parallaxBackgroundImage: '', // CSS syntax, e.g. "a.jpg"
+
+			// Parallax background size
+			parallaxBackgroundSize: '', // CSS syntax, e.g. "3000px 2000px"
+
+			// Amount of pixels to move the parallax background per slide step
+			parallaxBackgroundHorizontal: null,
+			parallaxBackgroundVertical: null,
+
+			// Number of slides away from the current that are visible
+			viewDistance: 3,
+
+			// Script dependencies to load
+			dependencies: []
+
+		},
+
+		// Flags if reveal.js is loaded (has dispatched the 'ready' event)
+		loaded = false,
+
+		// Flags if the overview mode is currently active
+		overview = false,
+
+		// The horizontal and vertical index of the currently active slide
+		indexh,
+		indexv,
+
+		// The previous and current slide HTML elements
+		previousSlide,
+		currentSlide,
+
+		previousBackground,
+
+		// Slides may hold a data-state attribute which we pick up and apply
+		// as a class to the body. This list contains the combined state of
+		// all current slides.
+		state = [],
+
+		// The current scale of the presentation (see width/height config)
+		scale = 1,
+
+		// CSS transform that is currently applied to the slides container,
+		// split into two groups
+		slidesTransform = { layout: '', overview: '' },
+
+		// Cached references to DOM elements
+		dom = {},
+
+		// Features supported by the browser, see #checkCapabilities()
+		features = {},
+
+		// Client is a mobile device, see #checkCapabilities()
+		isMobileDevice,
+
+		// Throttles mouse wheel navigation
+		lastMouseWheelStep = 0,
+
+		// Delays updates to the URL due to a Chrome thumbnailer bug
+		writeURLTimeout = 0,
+
+		// Flags if the interaction event listeners are bound
+		eventsAreBound = false,
+
+		// The current auto-slide duration
+		autoSlide = 0,
+
+		// Auto slide properties
+		autoSlidePlayer,
+		autoSlideTimeout = 0,
+		autoSlideStartTime = -1,
+		autoSlidePaused = false,
+
+		// Holds information about the currently ongoing touch input
+		touch = {
+			startX: 0,
+			startY: 0,
+			startSpan: 0,
+			startCount: 0,
+			captured: false,
+			threshold: 40
+		},
+
+		// Holds information about the keyboard shortcuts
+		keyboardShortcuts = {
+			'N  ,  SPACE':			'Next slide',
+			'P':					'Previous slide',
+			'←  ,  H':		'Navigate left',
+			'→  ,  L':		'Navigate right',
+			'↑  ,  K':		'Navigate up',
+			'↓  ,  J':		'Navigate down',
+			'Home':					'First slide',
+			'End':					'Last slide',
+			'B  ,  .':				'Pause',
+			'F':					'Fullscreen',
+			'ESC, O':				'Slide overview'
+		};
+
+	/**
+	 * Starts up the presentation if the client is capable.
+	 */
+	function initialize( options ) {
+
+		checkCapabilities();
+
+		if( !features.transforms2d && !features.transforms3d ) {
+			document.body.setAttribute( 'class', 'no-transforms' );
+
+			// Since JS won't be running any further, we load all lazy
+			// loading elements upfront
+			var images = toArray( document.getElementsByTagName( 'img' ) ),
+				iframes = toArray( document.getElementsByTagName( 'iframe' ) );
+
+			var lazyLoadable = images.concat( iframes );
+
+			for( var i = 0, len = lazyLoadable.length; i < len; i++ ) {
+				var element = lazyLoadable[i];
+				if( element.getAttribute( 'data-src' ) ) {
+					element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
+					element.removeAttribute( 'data-src' );
+				}
+			}
+
+			// If the browser doesn't support core features we won't be
+			// using JavaScript to control the presentation
+			return;
+		}
+
+		// Cache references to key DOM elements
+		dom.wrapper = document.querySelector( '.reveal' );
+		dom.slides = document.querySelector( '.reveal .slides' );
+
+		// Force a layout when the whole page, incl fonts, has loaded
+		window.addEventListener( 'load', layout, false );
+
+		var query = Reveal.getQueryHash();
+
+		// Do not accept new dependencies via query config to avoid
+		// the potential of malicious script injection
+		if( typeof query['dependencies'] !== 'undefined' ) delete query['dependencies'];
+
+		// Copy options over to our config object
+		extend( config, options );
+		extend( config, query );
+
+		// Hide the address bar in mobile browsers
+		hideAddressBar();
+
+		// Loads the dependencies and continues to #start() once done
+		load();
+
+	}
+
+	/**
+	 * Inspect the client to see what it's capable of, this
+	 * should only happens once per runtime.
+	 */
+	function checkCapabilities() {
+
+		features.transforms3d = 'WebkitPerspective' in document.body.style ||
+								'MozPerspective' in document.body.style ||
+								'msPerspective' in document.body.style ||
+								'OPerspective' in document.body.style ||
+								'perspective' in document.body.style;
+
+		features.transforms2d = 'WebkitTransform' in document.body.style ||
+								'MozTransform' in document.body.style ||
+								'msTransform' in document.body.style ||
+								'OTransform' in document.body.style ||
+								'transform' in document.body.style;
+
+		features.requestAnimationFrameMethod = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame;
+		features.requestAnimationFrame = typeof features.requestAnimationFrameMethod === 'function';
+
+		features.canvas = !!document.createElement( 'canvas' ).getContext;
+
+		features.touch = !!( 'ontouchstart' in window );
+
+		// Transitions in the overview are disabled in desktop and
+		// mobile Safari due to lag
+		features.overviewTransitions = !/Version\/[\d\.]+.*Safari/.test( navigator.userAgent );
+
+		isMobileDevice = /(iphone|ipod|ipad|android)/gi.test( navigator.userAgent );
+
+	}
+
+    /**
+     * Loads the dependencies of reveal.js. Dependencies are
+     * defined via the configuration option 'dependencies'
+     * and will be loaded prior to starting/binding reveal.js.
+     * Some dependencies may have an 'async' flag, if so they
+     * will load after reveal.js has been started up.
+     */
+	function load() {
+
+		var scripts = [],
+			scriptsAsync = [],
+			scriptsToPreload = 0;
+
+		// Called once synchronous scripts finish loading
+		function proceed() {
+			if( scriptsAsync.length ) {
+				// Load asynchronous scripts
+				head.js.apply( null, scriptsAsync );
+			}
+
+			start();
+		}
+
+		function loadScript( s ) {
+			head.ready( s.src.match( /([\w\d_\-]*)\.?js$|[^\\\/]*$/i )[0], function() {
+				// Extension may contain callback functions
+				if( typeof s.callback === 'function' ) {
+					s.callback.apply( this );
+				}
+
+				if( --scriptsToPreload === 0 ) {
+					proceed();
+				}
+			});
+		}
+
+		for( var i = 0, len = config.dependencies.length; i < len; i++ ) {
+			var s = config.dependencies[i];
+
+			// Load if there's no condition or the condition is truthy
+			if( !s.condition || s.condition() ) {
+				if( s.async ) {
+					scriptsAsync.push( s.src );
+				}
+				else {
+					scripts.push( s.src );
+				}
+
+				loadScript( s );
+			}
+		}
+
+		if( scripts.length ) {
+			scriptsToPreload = scripts.length;
+
+			// Load synchronous scripts
+			head.js.apply( null, scripts );
+		}
+		else {
+			proceed();
+		}
+
+	}
+
+	/**
+	 * Starts up reveal.js by binding input events and navigating
+	 * to the current URL deeplink if there is one.
+	 */
+	function start() {
+
+		// Make sure we've got all the DOM elements we need
+		setupDOM();
+
+		// Listen to messages posted to this window
+		setupPostMessage();
+
+		// Prevent iframes from scrolling the slides out of view
+		setupIframeScrollPrevention();
+
+		// Resets all vertical slides so that only the first is visible
+		resetVerticalSlides();
+
+		// Updates the presentation to match the current configuration values
+		configure();
+
+		// Read the initial hash
+		readURL();
+
+		// Update all backgrounds
+		updateBackground( true );
+
+		// Notify listeners that the presentation is ready but use a 1ms
+		// timeout to ensure it's not fired synchronously after #initialize()
+		setTimeout( function() {
+			// Enable transitions now that we're loaded
+			dom.slides.classList.remove( 'no-transition' );
+
+			loaded = true;
+
+			dispatchEvent( 'ready', {
+				'indexh': indexh,
+				'indexv': indexv,
+				'currentSlide': currentSlide
+			} );
+		}, 1 );
+
+		// Special setup and config is required when printing to PDF
+		if( isPrintingPDF() ) {
+			removeEventListeners();
+
+			// The document needs to have loaded for the PDF layout
+			// measurements to be accurate
+			if( document.readyState === 'complete' ) {
+				setupPDF();
+			}
+			else {
+				window.addEventListener( 'load', setupPDF );
+			}
+		}
+
+	}
+
+	/**
+	 * Finds and stores references to DOM elements which are
+	 * required by the presentation. If a required element is
+	 * not found, it is created.
+	 */
+	function setupDOM() {
+
+		// Prevent transitions while we're loading
+		dom.slides.classList.add( 'no-transition' );
+
+		// Background element
+		dom.background = createSingletonNode( dom.wrapper, 'div', 'backgrounds', null );
+
+		// Progress bar
+		dom.progress = createSingletonNode( dom.wrapper, 'div', 'progress', '<span></span>' );
+		dom.progressbar = dom.progress.querySelector( 'span' );
+
+		// Arrow controls
+		createSingletonNode( dom.wrapper, 'aside', 'controls',
+			'<button class="navigate-left" aria-label="previous slide"></button>' +
+			'<button class="navigate-right" aria-label="next slide"></button>' +
+			'<button class="navigate-up" aria-label="above slide"></button>' +
+			'<button class="navigate-down" aria-label="below slide"></button>' );
+
+		// Slide number
+		dom.slideNumber = createSingletonNode( dom.wrapper, 'div', 'slide-number', '' );
+
+		// Element containing notes that are visible to the audience
+		dom.speakerNotes = createSingletonNode( dom.wrapper, 'div', 'speaker-notes', null );
+		dom.speakerNotes.setAttribute( 'data-prevent-swipe', '' );
+
+		// Overlay graphic which is displayed during the paused mode
+		createSingletonNode( dom.wrapper, 'div', 'pause-overlay', null );
+
+		// Cache references to elements
+		dom.controls = document.querySelector( '.reveal .controls' );
+		dom.theme = document.querySelector( '#theme' );
+
+		dom.wrapper.setAttribute( 'role', 'application' );
+
+		// There can be multiple instances of controls throughout the page
+		dom.controlsLeft = toArray( document.querySelectorAll( '.navigate-left' ) );
+		dom.controlsRight = toArray( document.querySelectorAll( '.navigate-right' ) );
+		dom.controlsUp = toArray( document.querySelectorAll( '.navigate-up' ) );
+		dom.controlsDown = toArray( document.querySelectorAll( '.navigate-down' ) );
+		dom.controlsPrev = toArray( document.querySelectorAll( '.navigate-prev' ) );
+		dom.controlsNext = toArray( document.querySelectorAll( '.navigate-next' ) );
+
+		dom.statusDiv = createStatusDiv();
+	}
+
+	/**
+	 * Creates a hidden div with role aria-live to announce the
+	 * current slide content. Hide the div off-screen to make it
+	 * available only to Assistive Technologies.
+	 */
+	function createStatusDiv() {
+
+		var statusDiv = document.getElementById( 'aria-status-div' );
+		if( !statusDiv ) {
+			statusDiv = document.createElement( 'div' );
+			statusDiv.style.position = 'absolute';
+			statusDiv.style.height = '1px';
+			statusDiv.style.width = '1px';
+			statusDiv.style.overflow ='hidden';
+			statusDiv.style.clip = 'rect( 1px, 1px, 1px, 1px )';
+			statusDiv.setAttribute( 'id', 'aria-status-div' );
+			statusDiv.setAttribute( 'aria-live', 'polite' );
+			statusDiv.setAttribute( 'aria-atomic','true' );
+			dom.wrapper.appendChild( statusDiv );
+		}
+		return statusDiv;
+
+	}
+
+	/**
+	 * Configures the presentation for printing to a static
+	 * PDF.
+	 */
+	function setupPDF() {
+
+		var slideSize = getComputedSlideSize( window.innerWidth, window.innerHeight );
+
+		// Dimensions of the PDF pages
+		var pageWidth = Math.floor( slideSize.width * ( 1 + config.margin ) ),
+			pageHeight = Math.floor( slideSize.height * ( 1 + config.margin  ) );
+
+		// Dimensions of slides within the pages
+		var slideWidth = slideSize.width,
+			slideHeight = slideSize.height;
+
+		// Let the browser know what page size we want to print
+		injectStyleSheet( '@page{size:'+ pageWidth +'px '+ pageHeight +'px; margin: 0;}' );
+
+		// Limit the size of certain elements to the dimensions of the slide
+		injectStyleSheet( '.reveal section>img, .reveal section>video, .reveal section>iframe{max-width: '+ slideWidth +'px; max-height:'+ slideHeight +'px}' );
+
+		document.body.classList.add( 'print-pdf' );
+		document.body.style.width = pageWidth + 'px';
+		document.body.style.height = pageHeight + 'px';
+
+		// Add each slide's index as attributes on itself, we need these
+		// indices to generate slide numbers below
+		toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( hslide, h ) {
+			hslide.setAttribute( 'data-index-h', h );
+
+			if( hslide.classList.contains( 'stack' ) ) {
+				toArray( hslide.querySelectorAll( 'section' ) ).forEach( function( vslide, v ) {
+					vslide.setAttribute( 'data-index-h', h );
+					vslide.setAttribute( 'data-index-v', v );
+				} );
+			}
+		} );
+
+		// Slide and slide background layout
+		toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
+
+			// Vertical stacks are not centred since their section
+			// children will be
+			if( slide.classList.contains( 'stack' ) === false ) {
+				// Center the slide inside of the page, giving the slide some margin
+				var left = ( pageWidth - slideWidth ) / 2,
+					top = ( pageHeight - slideHeight ) / 2;
+
+				var contentHeight = getAbsoluteHeight( slide );
+				var numberOfPages = Math.max( Math.ceil( contentHeight / pageHeight ), 1 );
+
+				// Center slides vertically
+				if( numberOfPages === 1 && config.center || slide.classList.contains( 'center' ) ) {
+					top = Math.max( ( pageHeight - contentHeight ) / 2, 0 );
+				}
+
+				// Position the slide inside of the page
+				slide.style.left = left + 'px';
+				slide.style.top = top + 'px';
+				slide.style.width = slideWidth + 'px';
+
+				// TODO Backgrounds need to be multiplied when the slide
+				// stretches over multiple pages
+				var background = slide.querySelector( '.slide-background' );
+				if( background ) {
+					background.style.width = pageWidth + 'px';
+					background.style.height = ( pageHeight * numberOfPages ) + 'px';
+					background.style.top = -top + 'px';
+					background.style.left = -left + 'px';
+				}
+
+				// Inject notes if `showNotes` is enabled
+				if( config.showNotes ) {
+					var notes = getSlideNotes( slide );
+					if( notes ) {
+						var notesSpacing = 8;
+						var notesElement = document.createElement( 'div' );
+						notesElement.classList.add( 'speaker-notes' );
+						notesElement.classList.add( 'speaker-notes-pdf' );
+						notesElement.innerHTML = notes;
+						notesElement.style.left = ( notesSpacing - left ) + 'px';
+						notesElement.style.bottom = ( notesSpacing - top ) + 'px';
+						notesElement.style.width = ( pageWidth - notesSpacing*2 ) + 'px';
+						slide.appendChild( notesElement );
+					}
+				}
+
+				// Inject slide numbers if `slideNumbers` are enabled
+				if( config.slideNumber ) {
+					var slideNumberH = parseInt( slide.getAttribute( 'data-index-h' ), 10 ) + 1,
+						slideNumberV = parseInt( slide.getAttribute( 'data-index-v' ), 10 ) + 1;
+
+					var numberElement = document.createElement( 'div' );
+					numberElement.classList.add( 'slide-number' );
+					numberElement.classList.add( 'slide-number-pdf' );
+					numberElement.innerHTML = formatSlideNumber( slideNumberH, '.', slideNumberV );
+					background.appendChild( numberElement );
+				}
+			}
+
+		} );
+
+		// Show all fragments
+		toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' .fragment' ) ).forEach( function( fragment ) {
+			fragment.classList.add( 'visible' );
+		} );
+
+	}
+
+	/**
+	 * This is an unfortunate necessity. Iframes can trigger the
+	 * parent window to scroll, for example by focusing an input.
+	 * This scrolling can not be prevented by hiding overflow in
+	 * CSS so we have to resort to repeatedly checking if the
+	 * browser has decided to offset our slides :(
+	 */
+	function setupIframeScrollPrevention() {
+
+		if( dom.slides.querySelector( 'iframe' ) ) {
+			setInterval( function() {
+				if( dom.wrapper.scrollTop !== 0 || dom.wrapper.scrollLeft !== 0 ) {
+					dom.wrapper.scrollTop = 0;
+					dom.wrapper.scrollLeft = 0;
+				}
+			}, 500 );
+		}
+
+	}
+
+	/**
+	 * Creates an HTML element and returns a reference to it.
+	 * If the element already exists the existing instance will
+	 * be returned.
+	 */
+	function createSingletonNode( container, tagname, classname, innerHTML ) {
+
+		// Find all nodes matching the description
+		var nodes = container.querySelectorAll( '.' + classname );
+
+		// Check all matches to find one which is a direct child of
+		// the specified container
+		for( var i = 0; i < nodes.length; i++ ) {
+			var testNode = nodes[i];
+			if( testNode.parentNode === container ) {
+				return testNode;
+			}
+		}
+
+		// If no node was found, create it now
+		var node = document.createElement( tagname );
+		node.classList.add( classname );
+		if( typeof innerHTML === 'string' ) {
+			node.innerHTML = innerHTML;
+		}
+		container.appendChild( node );
+
+		return node;
+
+	}
+
+	/**
+	 * Creates the slide background elements and appends them
+	 * to the background container. One element is created per
+	 * slide no matter if the given slide has visible background.
+	 */
+	function createBackgrounds() {
+
+		var printMode = isPrintingPDF();
+
+		// Clear prior backgrounds
+		dom.background.innerHTML = '';
+		dom.background.classList.add( 'no-transition' );
+
+		// Iterate over all horizontal slides
+		toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( slideh ) {
+
+			var backgroundStack;
+
+			if( printMode ) {
+				backgroundStack = createBackground( slideh, slideh );
+			}
+			else {
+				backgroundStack = createBackground( slideh, dom.background );
+			}
+
+			// Iterate over all vertical slides
+			toArray( slideh.querySelectorAll( 'section' ) ).forEach( function( slidev ) {
+
+				if( printMode ) {
+					createBackground( slidev, slidev );
+				}
+				else {
+					createBackground( slidev, backgroundStack );
+				}
+
+				backgroundStack.classList.add( 'stack' );
+
+			} );
+
+		} );
+
+		// Add parallax background if specified
+		if( config.parallaxBackgroundImage ) {
+
+			dom.background.style.backgroundImage = 'url("' + config.parallaxBackgroundImage + '")';
+			dom.background.style.backgroundSize = config.parallaxBackgroundSize;
+
+			// Make sure the below properties are set on the element - these properties are
+			// needed for proper transitions to be set on the element via CSS. To remove
+			// annoying background slide-in effect when the presentation starts, apply
+			// these properties after short time delay
+			setTimeout( function() {
+				dom.wrapper.classList.add( 'has-parallax-background' );
+			}, 1 );
+
+		}
+		else {
+
+			dom.background.style.backgroundImage = '';
+			dom.wrapper.classList.remove( 'has-parallax-background' );
+
+		}
+
+	}
+
+	/**
+	 * Creates a background for the given slide.
+	 *
+	 * @param {HTMLElement} slide
+	 * @param {HTMLElement} container The element that the background
+	 * should be appended to
+	 */
+	function createBackground( slide, container ) {
+
+		var data = {
+			background: slide.getAttribute( 'data-background' ),
+			backgroundSize: slide.getAttribute( 'data-background-size' ),
+			backgroundImage: slide.getAttribute( 'data-background-image' ),
+			backgroundVideo: slide.getAttribute( 'data-background-video' ),
+			backgroundIframe: slide.getAttribute( 'data-background-iframe' ),
+			backgroundColor: slide.getAttribute( 'data-background-color' ),
+			backgroundRepeat: slide.getAttribute( 'data-background-repeat' ),
+			backgroundPosition: slide.getAttribute( 'data-background-position' ),
+			backgroundTransition: slide.getAttribute( 'data-background-transition' )
+		};
+
+		var element = document.createElement( 'div' );
+
+		// Carry over custom classes from the slide to the background
+		element.className = 'slide-background ' + slide.className.replace( /present|past|future/, '' );
+
+		if( data.background ) {
+			// Auto-wrap image urls in url(...)
+			if( /^(http|file|\/\/)/gi.test( data.background ) || /\.(svg|png|jpg|jpeg|gif|bmp)$/gi.test( data.background ) ) {
+				slide.setAttribute( 'data-background-image', data.background );
+			}
+			else {
+				element.style.background = data.background;
+			}
+		}
+
+		// Create a hash for this combination of background settings.
+		// This is used to determine when two slide backgrounds are
+		// the same.
+		if( data.background || data.backgroundColor || data.backgroundImage || data.backgroundVideo || data.backgroundIframe ) {
+			element.setAttribute( 'data-background-hash', data.background +
+															data.backgroundSize +
+															data.backgroundImage +
+															data.backgroundVideo +
+															data.backgroundIframe +
+															data.backgroundColor +
+															data.backgroundRepeat +
+															data.backgroundPosition +
+															data.backgroundTransition );
+		}
+
+		// Additional and optional background properties
+		if( data.backgroundSize ) element.style.backgroundSize = data.backgroundSize;
+		if( data.backgroundColor ) element.style.backgroundColor = data.backgroundColor;
+		if( data.backgroundRepeat ) element.style.backgroundRepeat = data.backgroundRepeat;
+		if( data.backgroundPosition ) element.style.backgroundPosition = data.backgroundPosition;
+		if( data.backgroundTransition ) element.setAttribute( 'data-background-transition', data.backgroundTransition );
+
+		container.appendChild( element );
+
+		// If backgrounds are being recreated, clear old classes
+		slide.classList.remove( 'has-dark-background' );
+		slide.classList.remove( 'has-light-background' );
+
+		// If this slide has a background color, add a class that
+		// signals if it is light or dark. If the slide has no background
+		// color, no class will be set
+		var computedBackgroundColor = window.getComputedStyle( element ).backgroundColor;
+		if( computedBackgroundColor ) {
+			var rgb = colorToRgb( computedBackgroundColor );
+
+			// Ignore fully transparent backgrounds. Some browsers return
+			// rgba(0,0,0,0) when reading the computed background color of
+			// an element with no background
+			if( rgb && rgb.a !== 0 ) {
+				if( colorBrightness( computedBackgroundColor ) < 128 ) {
+					slide.classList.add( 'has-dark-background' );
+				}
+				else {
+					slide.classList.add( 'has-light-background' );
+				}
+			}
+		}
+
+		return element;
+
+	}
+
+	/**
+	 * Registers a listener to postMessage events, this makes it
+	 * possible to call all reveal.js API methods from another
+	 * window. For example:
+	 *
+	 * revealWindow.postMessage( JSON.stringify({
+	 *   method: 'slide',
+	 *   args: [ 2 ]
+	 * }), '*' );
+	 */
+	function setupPostMessage() {
+
+		if( config.postMessage ) {
+			window.addEventListener( 'message', function ( event ) {
+				var data = event.data;
+
+				// Make sure we're dealing with JSON
+				if( typeof data === 'string' && data.charAt( 0 ) === '{' && data.charAt( data.length - 1 ) === '}' ) {
+					data = JSON.parse( data );
+
+					// Check if the requested method can be found
+					if( data.method && typeof Reveal[data.method] === 'function' ) {
+						Reveal[data.method].apply( Reveal, data.args );
+					}
+				}
+			}, false );
+		}
+
+	}
+
+	/**
+	 * Applies the configuration settings from the config
+	 * object. May be called multiple times.
+	 */
+	function configure( options ) {
+
+		var numberOfSlides = dom.wrapper.querySelectorAll( SLIDES_SELECTOR ).length;
+
+		dom.wrapper.classList.remove( config.transition );
+
+		// New config options may be passed when this method
+		// is invoked through the API after initialization
+		if( typeof options === 'object' ) extend( config, options );
+
+		// Force linear transition based on browser capabilities
+		if( features.transforms3d === false ) config.transition = 'linear';
+
+		dom.wrapper.classList.add( config.transition );
+
+		dom.wrapper.setAttribute( 'data-transition-speed', config.transitionSpeed );
+		dom.wrapper.setAttribute( 'data-background-transition', config.backgroundTransition );
+
+		dom.controls.style.display = config.controls ? 'block' : 'none';
+		dom.progress.style.display = config.progress ? 'block' : 'none';
+		dom.slideNumber.style.display = config.slideNumber && !isPrintingPDF() ? 'block' : 'none';
+
+		if( config.rtl ) {
+			dom.wrapper.classList.add( 'rtl' );
+		}
+		else {
+			dom.wrapper.classList.remove( 'rtl' );
+		}
+
+		if( config.center ) {
+			dom.wrapper.classList.add( 'center' );
+		}
+		else {
+			dom.wrapper.classList.remove( 'center' );
+		}
+
+		// Exit the paused mode if it was configured off
+		if( config.pause === false ) {
+			resume();
+		}
+
+		if( config.showNotes ) {
+			dom.speakerNotes.classList.add( 'visible' );
+		}
+		else {
+			dom.speakerNotes.classList.remove( 'visible' );
+		}
+
+		if( config.mouseWheel ) {
+			document.addEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
+			document.addEventListener( 'mousewheel', onDocumentMouseScroll, false );
+		}
+		else {
+			document.removeEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
+			document.removeEventListener( 'mousewheel', onDocumentMouseScroll, false );
+		}
+
+		// Rolling 3D links
+		if( config.rollingLinks ) {
+			enableRollingLinks();
+		}
+		else {
+			disableRollingLinks();
+		}
+
+		// Iframe link previews
+		if( config.previewLinks ) {
+			enablePreviewLinks();
+		}
+		else {
+			disablePreviewLinks();
+			enablePreviewLinks( '[data-preview-link]' );
+		}
+
+		// Remove existing auto-slide controls
+		if( autoSlidePlayer ) {
+			autoSlidePlayer.destroy();
+			autoSlidePlayer = null;
+		}
+
+		// Generate auto-slide controls if needed
+		if( numberOfSlides > 1 && config.autoSlide && config.autoSlideStoppable && features.canvas && features.requestAnimationFrame ) {
+			autoSlidePlayer = new Playback( dom.wrapper, function() {
+				return Math.min( Math.max( ( Date.now() - autoSlideStartTime ) / autoSlide, 0 ), 1 );
+			} );
+
+			autoSlidePlayer.on( 'click', onAutoSlidePlayerClick );
+			autoSlidePaused = false;
+		}
+
+		// When fragments are turned off they should be visible
+		if( config.fragments === false ) {
+			toArray( dom.slides.querySelectorAll( '.fragment' ) ).forEach( function( element ) {
+				element.classList.add( 'visible' );
+				element.classList.remove( 'current-fragment' );
+			} );
+		}
+
+		sync();
+
+	}
+
+	/**
+	 * Binds all event listeners.
+	 */
+	function addEventListeners() {
+
+		eventsAreBound = true;
+
+		window.addEventListener( 'hashchange', onWindowHashChange, false );
+		window.addEventListener( 'resize', onWindowResize, false );
+
+		if( config.touch ) {
+			dom.wrapper.addEventListener( 'touchstart', onTouchStart, false );
+			dom.wrapper.addEventListener( 'touchmove', onTouchMove, false );
+			dom.wrapper.addEventListener( 'touchend', onTouchEnd, false );
+
+			// Support pointer-style touch interaction as well
+			if( window.navigator.pointerEnabled ) {
+				// IE 11 uses un-prefixed version of pointer events
+				dom.wrapper.addEventListener( 'pointerdown', onPointerDown, false );
+				dom.wrapper.addEventListener( 'pointermove', onPointerMove, false );
+				dom.wrapper.addEventListener( 'pointerup', onPointerUp, false );
+			}
+			else if( window.navigator.msPointerEnabled ) {
+				// IE 10 uses prefixed version of pointer events
+				dom.wrapper.addEventListener( 'MSPointerDown', onPointerDown, false );
+				dom.wrapper.addEventListener( 'MSPointerMove', onPointerMove, false );
+				dom.wrapper.addEventListener( 'MSPointerUp', onPointerUp, false );
+			}
+		}
+
+		if( config.keyboard ) {
+			document.addEventListener( 'keydown', onDocumentKeyDown, false );
+			document.addEventListener( 'keypress', onDocumentKeyPress, false );
+		}
+
+		if( config.progress && dom.progress ) {
+			dom.progress.addEventListener( 'click', onProgressClicked, false );
+		}
+
+		if( config.focusBodyOnPageVisibilityChange ) {
+			var visibilityChange;
+
+			if( 'hidden' in document ) {
+				visibilityChange = 'visibilitychange';
+			}
+			else if( 'msHidden' in document ) {
+				visibilityChange = 'msvisibilitychange';
+			}
+			else if( 'webkitHidden' in document ) {
+				visibilityChange = 'webkitvisibilitychange';
+			}
+
+			if( visibilityChange ) {
+				document.addEventListener( visibilityChange, onPageVisibilityChange, false );
+			}
+		}
+
+		// Listen to both touch and click events, in case the device
+		// supports both
+		var pointerEvents = [ 'touchstart', 'click' ];
+
+		// Only support touch for Android, fixes double navigations in
+		// stock browser
+		if( navigator.userAgent.match( /android/gi ) ) {
+			pointerEvents = [ 'touchstart' ];
+		}
+
+		pointerEvents.forEach( function( eventName ) {
+			dom.controlsLeft.forEach( function( el ) { el.addEventListener( eventName, onNavigateLeftClicked, false ); } );
+			dom.controlsRight.forEach( function( el ) { el.addEventListener( eventName, onNavigateRightClicked, false ); } );
+			dom.controlsUp.forEach( function( el ) { el.addEventListener( eventName, onNavigateUpClicked, false ); } );
+			dom.controlsDown.forEach( function( el ) { el.addEventListener( eventName, onNavigateDownClicked, false ); } );
+			dom.controlsPrev.forEach( function( el ) { el.addEventListener( eventName, onNavigatePrevClicked, false ); } );
+			dom.controlsNext.forEach( function( el ) { el.addEventListener( eventName, onNavigateNextClicked, false ); } );
+		} );
+
+	}
+
+	/**
+	 * Unbinds all event listeners.
+	 */
+	function removeEventListeners() {
+
+		eventsAreBound = false;
+
+		document.removeEventListener( 'keydown', onDocumentKeyDown, false );
+		document.removeEventListener( 'keypress', onDocumentKeyPress, false );
+		window.removeEventListener( 'hashchange', onWindowHashChange, false );
+		window.removeEventListener( 'resize', onWindowResize, false );
+
+		dom.wrapper.removeEventListener( 'touchstart', onTouchStart, false );
+		dom.wrapper.removeEventListener( 'touchmove', onTouchMove, false );
+		dom.wrapper.removeEventListener( 'touchend', onTouchEnd, false );
+
+		// IE11
+		if( window.navigator.pointerEnabled ) {
+			dom.wrapper.removeEventListener( 'pointerdown', onPointerDown, false );
+			dom.wrapper.removeEventListener( 'pointermove', onPointerMove, false );
+			dom.wrapper.removeEventListener( 'pointerup', onPointerUp, false );
+		}
+		// IE10
+		else if( window.navigator.msPointerEnabled ) {
+			dom.wrapper.removeEventListener( 'MSPointerDown', onPointerDown, false );
+			dom.wrapper.removeEventListener( 'MSPointerMove', onPointerMove, false );
+			dom.wrapper.removeEventListener( 'MSPointerUp', onPointerUp, false );
+		}
+
+		if ( config.progress && dom.progress ) {
+			dom.progress.removeEventListener( 'click', onProgressClicked, false );
+		}
+
+		[ 'touchstart', 'click' ].forEach( function( eventName ) {
+			dom.controlsLeft.forEach( function( el ) { el.removeEventListener( eventName, onNavigateLeftClicked, false ); } );
+			dom.controlsRight.forEach( function( el ) { el.removeEventListener( eventName, onNavigateRightClicked, false ); } );
+			dom.controlsUp.forEach( function( el ) { el.removeEventListener( eventName, onNavigateUpClicked, false ); } );
+			dom.controlsDown.forEach( function( el ) { el.removeEventListener( eventName, onNavigateDownClicked, false ); } );
+			dom.controlsPrev.forEach( function( el ) { el.removeEventListener( eventName, onNavigatePrevClicked, false ); } );
+			dom.controlsNext.forEach( function( el ) { el.removeEventListener( eventName, onNavigateNextClicked, false ); } );
+		} );
+
+	}
+
+	/**
+	 * Extend object a with the properties of object b.
+	 * If there's a conflict, object b takes precedence.
+	 */
+	function extend( a, b ) {
+
+		for( var i in b ) {
+			a[ i ] = b[ i ];
+		}
+
+	}
+
+	/**
+	 * Converts the target object to an array.
+	 */
+	function toArray( o ) {
+
+		return Array.prototype.slice.call( o );
+
+	}
+
+	/**
+	 * Utility for deserializing a value.
+	 */
+	function deserialize( value ) {
+
+		if( typeof value === 'string' ) {
+			if( value === 'null' ) return null;
+			else if( value === 'true' ) return true;
+			else if( value === 'false' ) return false;
+			else if( value.match( /^\d+$/ ) ) return parseFloat( value );
+		}
+
+		return value;
+
+	}
+
+	/**
+	 * Measures the distance in pixels between point a
+	 * and point b.
+	 *
+	 * @param {Object} a point with x/y properties
+	 * @param {Object} b point with x/y properties
+	 */
+	function distanceBetween( a, b ) {
+
+		var dx = a.x - b.x,
+			dy = a.y - b.y;
+
+		return Math.sqrt( dx*dx + dy*dy );
+
+	}
+
+	/**
+	 * Applies a CSS transform to the target element.
+	 */
+	function transformElement( element, transform ) {
+
+		element.style.WebkitTransform = transform;
+		element.style.MozTransform = transform;
+		element.style.msTransform = transform;
+		element.style.transform = transform;
+
+	}
+
+	/**
+	 * Applies CSS transforms to the slides container. The container
+	 * is transformed from two separate sources: layout and the overview
+	 * mode.
+	 */
+	function transformSlides( transforms ) {
+
+		// Pick up new transforms from arguments
+		if( typeof transforms.layout === 'string' ) slidesTransform.layout = transforms.layout;
+		if( typeof transforms.overview === 'string' ) slidesTransform.overview = transforms.overview;
+
+		// Apply the transforms to the slides container
+		if( slidesTransform.layout ) {
+			transformElement( dom.slides, slidesTransform.layout + ' ' + slidesTransform.overview );
+		}
+		else {
+			transformElement( dom.slides, slidesTransform.overview );
+		}
+
+	}
+
+	/**
+	 * Injects the given CSS styles into the DOM.
+	 */
+	function injectStyleSheet( value ) {
+
+		var tag = document.createElement( 'style' );
+		tag.type = 'text/css';
+		if( tag.styleSheet ) {
+			tag.styleSheet.cssText = value;
+		}
+		else {
+			tag.appendChild( document.createTextNode( value ) );
+		}
+		document.getElementsByTagName( 'head' )[0].appendChild( tag );
+
+	}
+
+	/**
+	 * Converts various color input formats to an {r:0,g:0,b:0} object.
+	 *
+	 * @param {String} color The string representation of a color,
+	 * the following formats are supported:
+	 * - #000
+	 * - #000000
+	 * - rgb(0,0,0)
+	 */
+	function colorToRgb( color ) {
+
+		var hex3 = color.match( /^#([0-9a-f]{3})$/i );
+		if( hex3 && hex3[1] ) {
+			hex3 = hex3[1];
+			return {
+				r: parseInt( hex3.charAt( 0 ), 16 ) * 0x11,
+				g: parseInt( hex3.charAt( 1 ), 16 ) * 0x11,
+				b: parseInt( hex3.charAt( 2 ), 16 ) * 0x11
+			};
+		}
+
+		var hex6 = color.match( /^#([0-9a-f]{6})$/i );
+		if( hex6 && hex6[1] ) {
+			hex6 = hex6[1];
+			return {
+				r: parseInt( hex6.substr( 0, 2 ), 16 ),
+				g: parseInt( hex6.substr( 2, 2 ), 16 ),
+				b: parseInt( hex6.substr( 4, 2 ), 16 )
+			};
+		}
+
+		var rgb = color.match( /^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/i );
+		if( rgb ) {
+			return {
+				r: parseInt( rgb[1], 10 ),
+				g: parseInt( rgb[2], 10 ),
+				b: parseInt( rgb[3], 10 )
+			};
+		}
+
+		var rgba = color.match( /^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\,\s*([\d]+|[\d]*.[\d]+)\s*\)$/i );
+		if( rgba ) {
+			return {
+				r: parseInt( rgba[1], 10 ),
+				g: parseInt( rgba[2], 10 ),
+				b: parseInt( rgba[3], 10 ),
+				a: parseFloat( rgba[4] )
+			};
+		}
+
+		return null;
+
+	}
+
+	/**
+	 * Calculates brightness on a scale of 0-255.
+	 *
+	 * @param color See colorStringToRgb for supported formats.
+	 */
+	function colorBrightness( color ) {
+
+		if( typeof color === 'string' ) color = colorToRgb( color );
+
+		if( color ) {
+			return ( color.r * 299 + color.g * 587 + color.b * 114 ) / 1000;
+		}
+
+		return null;
+
+	}
+
+	/**
+	 * Retrieves the height of the given element by looking
+	 * at the position and height of its immediate children.
+	 */
+	function getAbsoluteHeight( element ) {
+
+		var height = 0;
+
+		if( element ) {
+			var absoluteChildren = 0;
+
+			toArray( element.childNodes ).forEach( function( child ) {
+
+				if( typeof child.offsetTop === 'number' && child.style ) {
+					// Count # of abs children
+					if( window.getComputedStyle( child ).position === 'absolute' ) {
+						absoluteChildren += 1;
+					}
+
+					height = Math.max( height, child.offsetTop + child.offsetHeight );
+				}
+
+			} );
+
+			// If there are no absolute children, use offsetHeight
+			if( absoluteChildren === 0 ) {
+				height = element.offsetHeight;
+			}
+
+		}
+
+		return height;
+
+	}
+
+	/**
+	 * Returns the remaining height within the parent of the
+	 * target element.
+	 *
+	 * remaining height = [ configured parent height ] - [ current parent height ]
+	 */
+	function getRemainingHeight( element, height ) {
+
+		height = height || 0;
+
+		if( element ) {
+			var newHeight, oldHeight = element.style.height;
+
+			// Change the .stretch element height to 0 in order find the height of all
+			// the other elements
+			element.style.height = '0px';
+			newHeight = height - element.parentNode.offsetHeight;
+
+			// Restore the old height, just in case
+			element.style.height = oldHeight + 'px';
+
+			return newHeight;
+		}
+
+		return height;
+
+	}
+
+	/**
+	 * Checks if this instance is being used to print a PDF.
+	 */
+	function isPrintingPDF() {
+
+		return ( /print-pdf/gi ).test( window.location.search );
+
+	}
+
+	/**
+	 * Hides the address bar if we're on a mobile device.
+	 */
+	function hideAddressBar() {
+
+		if( config.hideAddressBar && isMobileDevice ) {
+			// Events that should trigger the address bar to hide
+			window.addEventListener( 'load', removeAddressBar, false );
+			window.addEventListener( 'orientationchange', removeAddressBar, false );
+		}
+
+	}
+
+	/**
+	 * Causes the address bar to hide on mobile devices,
+	 * more vertical space ftw.
+	 */
+	function removeAddressBar() {
+
+		setTimeout( function() {
+			window.scrollTo( 0, 1 );
+		}, 10 );
+
+	}
+
+	/**
+	 * Dispatches an event of the specified type from the
+	 * reveal DOM element.
+	 */
+	function dispatchEvent( type, args ) {
+
+		var event = document.createEvent( 'HTMLEvents', 1, 2 );
+		event.initEvent( type, true, true );
+		extend( event, args );
+		dom.wrapper.dispatchEvent( event );
+
+		// If we're in an iframe, post each reveal.js event to the
+		// parent window. Used by the notes plugin
+		if( config.postMessageEvents && window.parent !== window.self ) {
+			window.parent.postMessage( JSON.stringify({ namespace: 'reveal', eventName: type, state: getState() }), '*' );
+		}
+
+	}
+
+	/**
+	 * Wrap all links in 3D goodness.
+	 */
+	function enableRollingLinks() {
+
+		if( features.transforms3d && !( 'msPerspective' in document.body.style ) ) {
+			var anchors = dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' a' );
+
+			for( var i = 0, len = anchors.length; i < len; i++ ) {
+				var anchor = anchors[i];
+
+				if( anchor.textContent && !anchor.querySelector( '*' ) && ( !anchor.className || !anchor.classList.contains( anchor, 'roll' ) ) ) {
+					var span = document.createElement('span');
+					span.setAttribute('data-title', anchor.text);
+					span.innerHTML = anchor.innerHTML;
+
+					anchor.classList.add( 'roll' );
+					anchor.innerHTML = '';
+					anchor.appendChild(span);
+				}
+			}
+		}
+
+	}
+
+	/**
+	 * Unwrap all 3D links.
+	 */
+	function disableRollingLinks() {
+
+		var anchors = dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' a.roll' );
+
+		for( var i = 0, len = anchors.length; i < len; i++ ) {
+			var anchor = anchors[i];
+			var span = anchor.querySelector( 'span' );
+
+			if( span ) {
+				anchor.classList.remove( 'roll' );
+				anchor.innerHTML = span.innerHTML;
+			}
+		}
+
+	}
+
+	/**
+	 * Bind preview frame links.
+	 */
+	function enablePreviewLinks( selector ) {
+
+		var anchors = toArray( document.querySelectorAll( selector ? selector : 'a' ) );
+
+		anchors.forEach( function( element ) {
+			if( /^(http|www)/gi.test( element.getAttribute( 'href' ) ) ) {
+				element.addEventListener( 'click', onPreviewLinkClicked, false );
+			}
+		} );
+
+	}
+
+	/**
+	 * Unbind preview frame links.
+	 */
+	function disablePreviewLinks() {
+
+		var anchors = toArray( document.querySelectorAll( 'a' ) );
+
+		anchors.forEach( function( element ) {
+			if( /^(http|www)/gi.test( element.getAttribute( 'href' ) ) ) {
+				element.removeEventListener( 'click', onPreviewLinkClicked, false );
+			}
+		} );
+
+	}
+
+	/**
+	 * Opens a preview window for the target URL.
+	 */
+	function showPreview( url ) {
+
+		closeOverlay();
+
+		dom.overlay = document.createElement( 'div' );
+		dom.overlay.classList.add( 'overlay' );
+		dom.overlay.classList.add( 'overlay-preview' );
+		dom.wrapper.appendChild( dom.overlay );
+
+		dom.overlay.innerHTML = [
+			'<header>',
+				'<a class="close" href="#"><span class="icon"></span></a>',
+				'<a class="external" href="'+ url +'" target="_blank"><span class="icon"></span></a>',
+			'</header>',
+			'<div class="spinner"></div>',
+			'<div class="viewport">',
+				'<iframe src="'+ url +'"></iframe>',
+			'</div>'
+		].join('');
+
+		dom.overlay.querySelector( 'iframe' ).addEventListener( 'load', function( event ) {
+			dom.overlay.classList.add( 'loaded' );
+		}, false );
+
+		dom.overlay.querySelector( '.close' ).addEventListener( 'click', function( event ) {
+			closeOverlay();
+			event.preventDefault();
+		}, false );
+
+		dom.overlay.querySelector( '.external' ).addEventListener( 'click', function( event ) {
+			closeOverlay();
+		}, false );
+
+		setTimeout( function() {
+			dom.overlay.classList.add( 'visible' );
+		}, 1 );
+
+	}
+
+	/**
+	 * Opens a overlay window with help material.
+	 */
+	function showHelp() {
+
+		if( config.help ) {
+
+			closeOverlay();
+
+			dom.overlay = document.createElement( 'div' );
+			dom.overlay.classList.add( 'overlay' );
+			dom.overlay.classList.add( 'overlay-help' );
+			dom.wrapper.appendChild( dom.overlay );
+
+			var html = '<p class="title">Keyboard Shortcuts</p><br/>';
+
+			html += '<table><th>KEY</th><th>ACTION</th>';
+			for( var key in keyboardShortcuts ) {
+				html += '<tr><td>' + key + '</td><td>' + keyboardShortcuts[ key ] + '</td></tr>';
+			}
+
+			html += '</table>';
+
+			dom.overlay.innerHTML = [
+				'<header>',
+					'<a class="close" href="#"><span class="icon"></span></a>',
+				'</header>',
+				'<div class="viewport">',
+					'<div class="viewport-inner">'+ html +'</div>',
+				'</div>'
+			].join('');
+
+			dom.overlay.querySelector( '.close' ).addEventListener( 'click', function( event ) {
+				closeOverlay();
+				event.preventDefault();
+			}, false );
+
+			setTimeout( function() {
+				dom.overlay.classList.add( 'visible' );
+			}, 1 );
+
+		}
+
+	}
+
+	/**
+	 * Closes any currently open overlay.
+	 */
+	function closeOverlay() {
+
+		if( dom.overlay ) {
+			dom.overlay.parentNode.removeChild( dom.overlay );
+			dom.overlay = null;
+		}
+
+	}
+
+	/**
+	 * Applies JavaScript-controlled layout rules to the
+	 * presentation.
+	 */
+	function layout() {
+
+		if( dom.wrapper && !isPrintingPDF() ) {
+
+			var size = getComputedSlideSize();
+
+			var slidePadding = 20; // TODO Dig this out of DOM
+
+			// Layout the contents of the slides
+			layoutSlideContents( config.width, config.height, slidePadding );
+
+			dom.slides.style.width = size.width + 'px';
+			dom.slides.style.height = size.height + 'px';
+
+			// Determine scale of content to fit within available space
+			scale = Math.min( size.presentationWidth / size.width, size.presentationHeight / size.height );
+
+			// Respect max/min scale settings
+			scale = Math.max( scale, config.minScale );
+			scale = Math.min( scale, config.maxScale );
+
+			// Don't apply any scaling styles if scale is 1
+			if( scale === 1 ) {
+				dom.slides.style.zoom = '';
+				dom.slides.style.left = '';
+				dom.slides.style.top = '';
+				dom.slides.style.bottom = '';
+				dom.slides.style.right = '';
+				transformSlides( { layout: '' } );
+			}
+			else {
+				// Use zoom to scale up in desktop Chrome so that content
+				// remains crisp. We don't use zoom to scale down since that
+				// can lead to shifts in text layout/line breaks.
+				if( scale > 1 && !isMobileDevice && /chrome/i.test( navigator.userAgent ) && typeof dom.slides.style.zoom !== 'undefined' ) {
+					dom.slides.style.zoom = scale;
+					dom.slides.style.left = '';
+					dom.slides.style.top = '';
+					dom.slides.style.bottom = '';
+					dom.slides.style.right = '';
+					transformSlides( { layout: '' } );
+				}
+				// Apply scale transform as a fallback
+				else {
+					dom.slides.style.zoom = '';
+					dom.slides.style.left = '50%';
+					dom.slides.style.top = '50%';
+					dom.slides.style.bottom = 'auto';
+					dom.slides.style.right = 'auto';
+					transformSlides( { layout: 'translate(-50%, -50%) scale('+ scale +')' } );
+				}
+			}
+
+			// Select all slides, vertical and horizontal
+			var slides = toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) );
+
+			for( var i = 0, len = slides.length; i < len; i++ ) {
+				var slide = slides[ i ];
+
+				// Don't bother updating invisible slides
+				if( slide.style.display === 'none' ) {
+					continue;
+				}
+
+				if( config.center || slide.classList.contains( 'center' ) ) {
+					// Vertical stacks are not centred since their section
+					// children will be
+					if( slide.classList.contains( 'stack' ) ) {
+						slide.style.top = 0;
+					}
+					else {
+						slide.style.top = Math.max( ( ( size.height - getAbsoluteHeight( slide ) ) / 2 ) - slidePadding, 0 ) + 'px';
+					}
+				}
+				else {
+					slide.style.top = '';
+				}
+
+			}
+
+			updateProgress();
+			updateParallax();
+
+		}
+
+	}
+
+	/**
+	 * Applies layout logic to the contents of all slides in
+	 * the presentation.
+	 */
+	function layoutSlideContents( width, height, padding ) {
+
+		// Handle sizing of elements with the 'stretch' class
+		toArray( dom.slides.querySelectorAll( 'section > .stretch' ) ).forEach( function( element ) {
+
+			// Determine how much vertical space we can use
+			var remainingHeight = getRemainingHeight( element, height );
+
+			// Consider the aspect ratio of media elements
+			if( /(img|video)/gi.test( element.nodeName ) ) {
+				var nw = element.naturalWidth || element.videoWidth,
+					nh = element.naturalHeight || element.videoHeight;
+
+				var es = Math.min( width / nw, remainingHeight / nh );
+
+				element.style.width = ( nw * es ) + 'px';
+				element.style.height = ( nh * es ) + 'px';
+
+			}
+			else {
+				element.style.width = width + 'px';
+				element.style.height = remainingHeight + 'px';
+			}
+
+		} );
+
+	}
+
+	/**
+	 * Calculates the computed pixel size of our slides. These
+	 * values are based on the width and height configuration
+	 * options.
+	 */
+	function getComputedSlideSize( presentationWidth, presentationHeight ) {
+
+		var size = {
+			// Slide size
+			width: config.width,
+			height: config.height,
+
+			// Presentation size
+			presentationWidth: presentationWidth || dom.wrapper.offsetWidth,
+			presentationHeight: presentationHeight || dom.wrapper.offsetHeight
+		};
+
+		// Reduce available space by margin
+		size.presentationWidth -= ( size.presentationWidth * config.margin );
+		size.presentationHeight -= ( size.presentationHeight * config.margin );
+
+		// Slide width may be a percentage of available width
+		if( typeof size.width === 'string' && /%$/.test( size.width ) ) {
+			size.width = parseInt( size.width, 10 ) / 100 * size.presentationWidth;
+		}
+
+		// Slide height may be a percentage of available height
+		if( typeof size.height === 'string' && /%$/.test( size.height ) ) {
+			size.height = parseInt( size.height, 10 ) / 100 * size.presentationHeight;
+		}
+
+		return size;
+
+	}
+
+	/**
+	 * Stores the vertical index of a stack so that the same
+	 * vertical slide can be selected when navigating to and
+	 * from the stack.
+	 *
+	 * @param {HTMLElement} stack The vertical stack element
+	 * @param {int} v Index to memorize
+	 */
+	function setPreviousVerticalIndex( stack, v ) {
+
+		if( typeof stack === 'object' && typeof stack.setAttribute === 'function' ) {
+			stack.setAttribute( 'data-previous-indexv', v || 0 );
+		}
+
+	}
+
+	/**
+	 * Retrieves the vertical index which was stored using
+	 * #setPreviousVerticalIndex() or 0 if no previous index
+	 * exists.
+	 *
+	 * @param {HTMLElement} stack The vertical stack element
+	 */
+	function getPreviousVerticalIndex( stack ) {
+
+		if( typeof stack === 'object' && typeof stack.setAttribute === 'function' && stack.classList.contains( 'stack' ) ) {
+			// Prefer manually defined start-indexv
+			var attributeName = stack.hasAttribute( 'data-start-indexv' ) ? 'data-start-indexv' : 'data-previous-indexv';
+
+			return parseInt( stack.getAttribute( attributeName ) || 0, 10 );
+		}
+
+		return 0;
+
+	}
+
+	/**
+	 * Displays the overview of slides (quick nav) by scaling
+	 * down and arranging all slide elements.
+	 */
+	function activateOverview() {
+
+		// Only proceed if enabled in config
+		if( config.overview && !isOverview() ) {
+
+			overview = true;
+
+			dom.wrapper.classList.add( 'overview' );
+			dom.wrapper.classList.remove( 'overview-deactivating' );
+
+			if( features.overviewTransitions ) {
+				setTimeout( function() {
+					dom.wrapper.classList.add( 'overview-animated' );
+				}, 1 );
+			}
+
+			// Don't auto-slide while in overview mode
+			cancelAutoSlide();
+
+			// Move the backgrounds element into the slide container to
+			// that the same scaling is applied
+			dom.slides.appendChild( dom.background );
+
+			// Clicking on an overview slide navigates to it
+			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
+				if( !slide.classList.contains( 'stack' ) ) {
+					slide.addEventListener( 'click', onOverviewSlideClicked, true );
+				}
+			} );
+
+			updateSlidesVisibility();
+			layoutOverview();
+			updateOverview();
+
+			layout();
+
+			// Notify observers of the overview showing
+			dispatchEvent( 'overviewshown', {
+				'indexh': indexh,
+				'indexv': indexv,
+				'currentSlide': currentSlide
+			} );
+
+		}
+
+	}
+
+	/**
+	 * Uses CSS transforms to position all slides in a grid for
+	 * display inside of the overview mode.
+	 */
+	function layoutOverview() {
+
+		var margin = 70;
+		var slideWidth = config.width + margin,
+			slideHeight = config.height + margin;
+
+		// Reverse in RTL mode
+		if( config.rtl ) {
+			slideWidth = -slideWidth;
+		}
+
+		// Layout slides
+		toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( hslide, h ) {
+			hslide.setAttribute( 'data-index-h', h );
+			transformElement( hslide, 'translate3d(' + ( h * slideWidth ) + 'px, 0, 0)' );
+
+			if( hslide.classList.contains( 'stack' ) ) {
+
+				toArray( hslide.querySelectorAll( 'section' ) ).forEach( function( vslide, v ) {
+					vslide.setAttribute( 'data-index-h', h );
+					vslide.setAttribute( 'data-index-v', v );
+
+					transformElement( vslide, 'translate3d(0, ' + ( v * slideHeight ) + 'px, 0)' );
+				} );
+
+			}
+		} );
+
+		// Layout slide backgrounds
+		toArray( dom.background.childNodes ).forEach( function( hbackground, h ) {
+			transformElement( hbackground, 'translate3d(' + ( h * slideWidth ) + 'px, 0, 0)' );
+
+			toArray( hbackground.querySelectorAll( '.slide-background' ) ).forEach( function( vbackground, v ) {
+				transformElement( vbackground, 'translate3d(0, ' + ( v * slideHeight ) + 'px, 0)' );
+			} );
+		} );
+
+	}
+
+	/**
+	 * Moves the overview viewport to the current slides.
+	 * Called each time the current slide changes.
+	 */
+	function updateOverview() {
+
+		var margin = 70;
+		var slideWidth = config.width + margin,
+			slideHeight = config.height + margin;
+
+		// Reverse in RTL mode
+		if( config.rtl ) {
+			slideWidth = -slideWidth;
+		}
+
+		transformSlides( {
+			overview: [
+				'translateX('+ ( -indexh * slideWidth ) +'px)',
+				'translateY('+ ( -indexv * slideHeight ) +'px)',
+				'translateZ('+ ( window.innerWidth < 400 ? -1000 : -2500 ) +'px)'
+			].join( ' ' )
+		} );
+
+	}
+
+	/**
+	 * Exits the slide overview and enters the currently
+	 * active slide.
+	 */
+	function deactivateOverview() {
+
+		// Only proceed if enabled in config
+		if( config.overview ) {
+
+			overview = false;
+
+			dom.wrapper.classList.remove( 'overview' );
+			dom.wrapper.classList.remove( 'overview-animated' );
+
+			// Temporarily add a class so that transitions can do different things
+			// depending on whether they are exiting/entering overview, or just
+			// moving from slide to slide
+			dom.wrapper.classList.add( 'overview-deactivating' );
+
+			setTimeout( function () {
+				dom.wrapper.classList.remove( 'overview-deactivating' );
+			}, 1 );
+
+			// Move the background element back out
+			dom.wrapper.appendChild( dom.background );
+
+			// Clean up changes made to slides
+			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
+				transformElement( slide, '' );
+
+				slide.removeEventListener( 'click', onOverviewSlideClicked, true );
+			} );
+
+			// Clean up changes made to backgrounds
+			toArray( dom.background.querySelectorAll( '.slide-background' ) ).forEach( function( background ) {
+				transformElement( background, '' );
+			} );
+
+			transformSlides( { overview: '' } );
+
+			slide( indexh, indexv );
+
+			layout();
+
+			cueAutoSlide();
+
+			// Notify observers of the overview hiding
+			dispatchEvent( 'overviewhidden', {
+				'indexh': indexh,
+				'indexv': indexv,
+				'currentSlide': currentSlide
+			} );
+
+		}
+	}
+
+	/**
+	 * Toggles the slide overview mode on and off.
+	 *
+	 * @param {Boolean} override Optional flag which overrides the
+	 * toggle logic and forcibly sets the desired state. True means
+	 * overview is open, false means it's closed.
+	 */
+	function toggleOverview( override ) {
+
+		if( typeof override === 'boolean' ) {
+			override ? activateOverview() : deactivateOverview();
+		}
+		else {
+			isOverview() ? deactivateOverview() : activateOverview();
+		}
+
+	}
+
+	/**
+	 * Checks if the overview is currently active.
+	 *
+	 * @return {Boolean} true if the overview is active,
+	 * false otherwise
+	 */
+	function isOverview() {
+
+		return overview;
+
+	}
+
+	/**
+	 * Checks if the current or specified slide is vertical
+	 * (nested within another slide).
+	 *
+	 * @param {HTMLElement} slide [optional] The slide to check
+	 * orientation of
+	 */
+	function isVerticalSlide( slide ) {
+
+		// Prefer slide argument, otherwise use current slide
+		slide = slide ? slide : currentSlide;
+
+		return slide && slide.parentNode && !!slide.parentNode.nodeName.match( /section/i );
+
+	}
+
+	/**
+	 * Handling the fullscreen functionality via the fullscreen API
+	 *
+	 * @see http://fullscreen.spec.whatwg.org/
+	 * @see https://developer.mozilla.org/en-US/docs/DOM/Using_fullscreen_mode
+	 */
+	function enterFullscreen() {
+
+		var element = document.body;
+
+		// Check which implementation is available
+		var requestMethod = element.requestFullScreen ||
+							element.webkitRequestFullscreen ||
+							element.webkitRequestFullScreen ||
+							element.mozRequestFullScreen ||
+							element.msRequestFullscreen;
+
+		if( requestMethod ) {
+			requestMethod.apply( element );
+		}
+
+	}
+
+	/**
+	 * Enters the paused mode which fades everything on screen to
+	 * black.
+	 */
+	function pause() {
+
+		if( config.pause ) {
+			var wasPaused = dom.wrapper.classList.contains( 'paused' );
+
+			cancelAutoSlide();
+			dom.wrapper.classList.add( 'paused' );
+
+			if( wasPaused === false ) {
+				dispatchEvent( 'paused' );
+			}
+		}
+
+	}
+
+	/**
+	 * Exits from the paused mode.
+	 */
+	function resume() {
+
+		var wasPaused = dom.wrapper.classList.contains( 'paused' );
+		dom.wrapper.classList.remove( 'paused' );
+
+		cueAutoSlide();
+
+		if( wasPaused ) {
+			dispatchEvent( 'resumed' );
+		}
+
+	}
+
+	/**
+	 * Toggles the paused mode on and off.
+	 */
+	function togglePause( override ) {
+
+		if( typeof override === 'boolean' ) {
+			override ? pause() : resume();
+		}
+		else {
+			isPaused() ? resume() : pause();
+		}
+
+	}
+
+	/**
+	 * Checks if we are currently in the paused mode.
+	 */
+	function isPaused() {
+
+		return dom.wrapper.classList.contains( 'paused' );
+
+	}
+
+	/**
+	 * Toggles the auto slide mode on and off.
+	 *
+	 * @param {Boolean} override Optional flag which sets the desired state.
+	 * True means autoplay starts, false means it stops.
+	 */
+
+	function toggleAutoSlide( override ) {
+
+		if( typeof override === 'boolean' ) {
+			override ? resumeAutoSlide() : pauseAutoSlide();
+		}
+
+		else {
+			autoSlidePaused ? resumeAutoSlide() : pauseAutoSlide();
+		}
+
+	}
+
+	/**
+	 * Checks if the auto slide mode is currently on.
+	 */
+	function isAutoSliding() {
+
+		return !!( autoSlide && !autoSlidePaused );
+
+	}
+
+	/**
+	 * Steps from the current point in the presentation to the
+	 * slide which matches the specified horizontal and vertical
+	 * indices.
+	 *
+	 * @param {int} h Horizontal index of the target slide
+	 * @param {int} v Vertical index of the target slide
+	 * @param {int} f Optional index of a fragment within the
+	 * target slide to activate
+	 * @param {int} o Optional origin for use in multimaster environments
+	 */
+	function slide( h, v, f, o ) {
+
+		// Remember where we were at before
+		previousSlide = currentSlide;
+
+		// Query all horizontal slides in the deck
+		var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );
+
+		// If no vertical index is specified and the upcoming slide is a
+		// stack, resume at its previous vertical index
+		if( v === undefined && !isOverview() ) {
+			v = getPreviousVerticalIndex( horizontalSlides[ h ] );
+		}
+
+		// If we were on a vertical stack, remember what vertical index
+		// it was on so we can resume at the same position when returning
+		if( previousSlide && previousSlide.parentNode && previousSlide.parentNode.classList.contains( 'stack' ) ) {
+			setPreviousVerticalIndex( previousSlide.parentNode, indexv );
+		}
+
+		// Remember the state before this slide
+		var stateBefore = state.concat();
+
+		// Reset the state array
+		state.length = 0;
+
+		var indexhBefore = indexh || 0,
+			indexvBefore = indexv || 0;
+
+		// Activate and transition to the new slide
+		indexh = updateSlides( HORIZONTAL_SLIDES_SELECTOR, h === undefined ? indexh : h );
+		indexv = updateSlides( VERTICAL_SLIDES_SELECTOR, v === undefined ? indexv : v );
+
+		// Update the visibility of slides now that the indices have changed
+		updateSlidesVisibility();
+
+		layout();
+
+		// Apply the new state
+		stateLoop: for( var i = 0, len = state.length; i < len; i++ ) {
+			// Check if this state existed on the previous slide. If it
+			// did, we will avoid adding it repeatedly
+			for( var j = 0; j < stateBefore.length; j++ ) {
+				if( stateBefore[j] === state[i] ) {
+					stateBefore.splice( j, 1 );
+					continue stateLoop;
+				}
+			}
+
+			document.documentElement.classList.add( state[i] );
+
+			// Dispatch custom event matching the state's name
+			dispatchEvent( state[i] );
+		}
+
+		// Clean up the remains of the previous state
+		while( stateBefore.length ) {
+			document.documentElement.classList.remove( stateBefore.pop() );
+		}
+
+		// Update the overview if it's currently active
+		if( isOverview() ) {
+			updateOverview();
+		}
+
+		// Find the current horizontal slide and any possible vertical slides
+		// within it
+		var currentHorizontalSlide = horizontalSlides[ indexh ],
+			currentVerticalSlides = currentHorizontalSlide.querySelectorAll( 'section' );
+
+		// Store references to the previous and current slides
+		currentSlide = currentVerticalSlides[ indexv ] || currentHorizontalSlide;
+
+		// Show fragment, if specified
+		if( typeof f !== 'undefined' ) {
+			navigateFragment( f );
+		}
+
+		// Dispatch an event if the slide changed
+		var slideChanged = ( indexh !== indexhBefore || indexv !== indexvBefore );
+		if( slideChanged ) {
+			dispatchEvent( 'slidechanged', {
+				'indexh': indexh,
+				'indexv': indexv,
+				'previousSlide': previousSlide,
+				'currentSlide': currentSlide,
+				'origin': o
+			} );
+		}
+		else {
+			// Ensure that the previous slide is never the same as the current
+			previousSlide = null;
+		}
+
+		// Solves an edge case where the previous slide maintains the
+		// 'present' class when navigating between adjacent vertical
+		// stacks
+		if( previousSlide ) {
+			previousSlide.classList.remove( 'present' );
+			previousSlide.setAttribute( 'aria-hidden', 'true' );
+
+			// Reset all slides upon navigate to home
+			// Issue: #285
+			if ( dom.wrapper.querySelector( HOME_SLIDE_SELECTOR ).classList.contains( 'present' ) ) {
+				// Launch async task
+				setTimeout( function () {
+					var slides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.stack') ), i;
+					for( i in slides ) {
+						if( slides[i] ) {
+							// Reset stack
+							setPreviousVerticalIndex( slides[i], 0 );
+						}
+					}
+				}, 0 );
+			}
+		}
+
+		// Handle embedded content
+		if( slideChanged || !previousSlide ) {
+			stopEmbeddedContent( previousSlide );
+			startEmbeddedContent( currentSlide );
+		}
+
+		// Announce the current slide contents, for screen readers
+		dom.statusDiv.textContent = currentSlide.textContent;
+
+		updateControls();
+		updateProgress();
+		updateBackground();
+		updateParallax();
+		updateSlideNumber();
+		updateNotes();
+
+		// Update the URL hash
+		writeURL();
+
+		cueAutoSlide();
+
+	}
+
+	/**
+	 * Syncs the presentation with the current DOM. Useful
+	 * when new slides or control elements are added or when
+	 * the configuration has changed.
+	 */
+	function sync() {
+
+		// Subscribe to input
+		removeEventListeners();
+		addEventListeners();
+
+		// Force a layout to make sure the current config is accounted for
+		layout();
+
+		// Reflect the current autoSlide value
+		autoSlide = config.autoSlide;
+
+		// Start auto-sliding if it's enabled
+		cueAutoSlide();
+
+		// Re-create the slide backgrounds
+		createBackgrounds();
+
+		// Write the current hash to the URL
+		writeURL();
+
+		sortAllFragments();
+
+		updateControls();
+		updateProgress();
+		updateBackground( true );
+		updateSlideNumber();
+		updateSlidesVisibility();
+		updateNotes();
+
+		formatEmbeddedContent();
+		startEmbeddedContent( currentSlide );
+
+		if( isOverview() ) {
+			layoutOverview();
+		}
+
+	}
+
+	/**
+	 * Resets all vertical slides so that only the first
+	 * is visible.
+	 */
+	function resetVerticalSlides() {
+
+		var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
+		horizontalSlides.forEach( function( horizontalSlide ) {
+
+			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
+			verticalSlides.forEach( function( verticalSlide, y ) {
+
+				if( y > 0 ) {
+					verticalSlide.classList.remove( 'present' );
+					verticalSlide.classList.remove( 'past' );
+					verticalSlide.classList.add( 'future' );
+					verticalSlide.setAttribute( 'aria-hidden', 'true' );
+				}
+
+			} );
+
+		} );
+
+	}
+
+	/**
+	 * Sorts and formats all of fragments in the
+	 * presentation.
+	 */
+	function sortAllFragments() {
+
+		var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
+		horizontalSlides.forEach( function( horizontalSlide ) {
+
+			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
+			verticalSlides.forEach( function( verticalSlide, y ) {
+
+				sortFragments( verticalSlide.querySelectorAll( '.fragment' ) );
+
+			} );
+
+			if( verticalSlides.length === 0 ) sortFragments( horizontalSlide.querySelectorAll( '.fragment' ) );
+
+		} );
+
+	}
+
+	/**
+	 * Updates one dimension of slides by showing the slide
+	 * with the specified index.
+	 *
+	 * @param {String} selector A CSS selector that will fetch
+	 * the group of slides we are working with
+	 * @param {Number} index The index of the slide that should be
+	 * shown
+	 *
+	 * @return {Number} The index of the slide that is now shown,
+	 * might differ from the passed in index if it was out of
+	 * bounds.
+	 */
+	function updateSlides( selector, index ) {
+
+		// Select all slides and convert the NodeList result to
+		// an array
+		var slides = toArray( dom.wrapper.querySelectorAll( selector ) ),
+			slidesLength = slides.length;
+
+		var printMode = isPrintingPDF();
+
+		if( slidesLength ) {
+
+			// Should the index loop?
+			if( config.loop ) {
+				index %= slidesLength;
+
+				if( index < 0 ) {
+					index = slidesLength + index;
+				}
+			}
+
+			// Enforce max and minimum index bounds
+			index = Math.max( Math.min( index, slidesLength - 1 ), 0 );
+
+			for( var i = 0; i < slidesLength; i++ ) {
+				var element = slides[i];
+
+				var reverse = config.rtl && !isVerticalSlide( element );
+
+				element.classList.remove( 'past' );
+				element.classList.remove( 'present' );
+				element.classList.remove( 'future' );
+
+				// http://www.w3.org/html/wg/drafts/html/master/editing.html#the-hidden-attribute
+				element.setAttribute( 'hidden', '' );
+				element.setAttribute( 'aria-hidden', 'true' );
+
+				// If this element contains vertical slides
+				if( element.querySelector( 'section' ) ) {
+					element.classList.add( 'stack' );
+				}
+
+				// If we're printing static slides, all slides are "present"
+				if( printMode ) {
+					element.classList.add( 'present' );
+					continue;
+				}
+
+				if( i < index ) {
+					// Any element previous to index is given the 'past' class
+					element.classList.add( reverse ? 'future' : 'past' );
+
+					if( config.fragments ) {
+						var pastFragments = toArray( element.querySelectorAll( '.fragment' ) );
+
+						// Show all fragments on prior slides
+						while( pastFragments.length ) {
+							var pastFragment = pastFragments.pop();
+							pastFragment.classList.add( 'visible' );
+							pastFragment.classList.remove( 'current-fragment' );
+						}
+					}
+				}
+				else if( i > index ) {
+					// Any element subsequent to index is given the 'future' class
+					element.classList.add( reverse ? 'past' : 'future' );
+
+					if( config.fragments ) {
+						var futureFragments = toArray( element.querySelectorAll( '.fragment.visible' ) );
+
+						// No fragments in future slides should be visible ahead of time
+						while( futureFragments.length ) {
+							var futureFragment = futureFragments.pop();
+							futureFragment.classList.remove( 'visible' );
+							futureFragment.classList.remove( 'current-fragment' );
+						}
+					}
+				}
+			}
+
+			// Mark the current slide as present
+			slides[index].classList.add( 'present' );
+			slides[index].removeAttribute( 'hidden' );
+			slides[index].removeAttribute( 'aria-hidden' );
+
+			// If this slide has a state associated with it, add it
+			// onto the current state of the deck
+			var slideState = slides[index].getAttribute( 'data-state' );
+			if( slideState ) {
+				state = state.concat( slideState.split( ' ' ) );
+			}
+
+		}
+		else {
+			// Since there are no slides we can't be anywhere beyond the
+			// zeroth index
+			index = 0;
+		}
+
+		return index;
+
+	}
+
+	/**
+	 * Optimization method; hide all slides that are far away
+	 * from the present slide.
+	 */
+	function updateSlidesVisibility() {
+
+		// Select all slides and convert the NodeList result to
+		// an array
+		var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ),
+			horizontalSlidesLength = horizontalSlides.length,
+			distanceX,
+			distanceY;
+
+		if( horizontalSlidesLength && typeof indexh !== 'undefined' ) {
+
+			// The number of steps away from the present slide that will
+			// be visible
+			var viewDistance = isOverview() ? 10 : config.viewDistance;
+
+			// Limit view distance on weaker devices
+			if( isMobileDevice ) {
+				viewDistance = isOverview() ? 6 : 2;
+			}
+
+			// All slides need to be visible when exporting to PDF
+			if( isPrintingPDF() ) {
+				viewDistance = Number.MAX_VALUE;
+			}
+
+			for( var x = 0; x < horizontalSlidesLength; x++ ) {
+				var horizontalSlide = horizontalSlides[x];
+
+				var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) ),
+					verticalSlidesLength = verticalSlides.length;
+
+				// Determine how far away this slide is from the present
+				distanceX = Math.abs( ( indexh || 0 ) - x ) || 0;
+
+				// If the presentation is looped, distance should measure
+				// 1 between the first and last slides
+				if( config.loop ) {
+					distanceX = Math.abs( ( ( indexh || 0 ) - x ) % ( horizontalSlidesLength - viewDistance ) ) || 0;
+				}
+
+				// Show the horizontal slide if it's within the view distance
+				if( distanceX < viewDistance ) {
+					showSlide( horizontalSlide );
+				}
+				else {
+					hideSlide( horizontalSlide );
+				}
+
+				if( verticalSlidesLength ) {
+
+					var oy = getPreviousVerticalIndex( horizontalSlide );
+
+					for( var y = 0; y < verticalSlidesLength; y++ ) {
+						var verticalSlide = verticalSlides[y];
+
+						distanceY = x === ( indexh || 0 ) ? Math.abs( ( indexv || 0 ) - y ) : Math.abs( y - oy );
+
+						if( distanceX + distanceY < viewDistance ) {
+							showSlide( verticalSlide );
+						}
+						else {
+							hideSlide( verticalSlide );
+						}
+					}
+
+				}
+			}
+
+		}
+
+	}
+
+	/**
+	 * Pick up notes from the current slide and display tham
+	 * to the viewer.
+	 *
+	 * @see `showNotes` config value
+	 */
+	function updateNotes() {
+
+		if( config.showNotes && dom.speakerNotes && currentSlide && !isPrintingPDF() ) {
+
+			dom.speakerNotes.innerHTML = getSlideNotes() || '';
+
+		}
+
+	}
+
+	/**
+	 * Updates the progress bar to reflect the current slide.
+	 */
+	function updateProgress() {
+
+		// Update progress if enabled
+		if( config.progress && dom.progressbar ) {
+
+			dom.progressbar.style.width = getProgress() * dom.wrapper.offsetWidth + 'px';
+
+		}
+
+	}
+
+	/**
+	 * Updates the slide number div to reflect the current slide.
+	 *
+	 * The following slide number formats are available:
+	 *  "h.v": 	horizontal . vertical slide number (default)
+	 *  "h/v": 	horizontal / vertical slide number
+	 *    "c": 	flattened slide number
+	 *  "c/t": 	flattened slide number / total slides
+	 */
+	function updateSlideNumber() {
+
+		// Update slide number if enabled
+		if( config.slideNumber && dom.slideNumber ) {
+
+			var value = [];
+			var format = 'h.v';
+
+			// Check if a custom number format is available
+			if( typeof config.slideNumber === 'string' ) {
+				format = config.slideNumber;
+			}
+
+			switch( format ) {
+				case 'c':
+					value.push( getSlidePastCount() + 1 );
+					break;
+				case 'c/t':
+					value.push( getSlidePastCount() + 1, '/', getTotalSlides() );
+					break;
+				case 'h/v':
+					value.push( indexh + 1 );
+					if( isVerticalSlide() ) value.push( '/', indexv + 1 );
+					break;
+				default:
+					value.push( indexh + 1 );
+					if( isVerticalSlide() ) value.push( '.', indexv + 1 );
+			}
+
+			dom.slideNumber.innerHTML = formatSlideNumber( value[0], value[1], value[2] );
+		}
+
+	}
+
+	/**
+	 * Applies HTML formatting to a slide number before it's
+	 * written to the DOM.
+	 */
+	function formatSlideNumber( a, delimiter, b ) {
+
+		if( typeof b === 'number' && !isNaN( b ) ) {
+			return  '<span class="slide-number-a">'+ a +'</span>' +
+					'<span class="slide-number-delimiter">'+ delimiter +'</span>' +
+					'<span class="slide-number-b">'+ b +'</span>';
+		}
+		else {
+			return '<span class="slide-number-a">'+ a +'</span>';
+		}
+
+	}
+
+	/**
+	 * Updates the state of all control/navigation arrows.
+	 */
+	function updateControls() {
+
+		var routes = availableRoutes();
+		var fragments = availableFragments();
+
+		// Remove the 'enabled' class from all directions
+		dom.controlsLeft.concat( dom.controlsRight )
+						.concat( dom.controlsUp )
+						.concat( dom.controlsDown )
+						.concat( dom.controlsPrev )
+						.concat( dom.controlsNext ).forEach( function( node ) {
+			node.classList.remove( 'enabled' );
+			node.classList.remove( 'fragmented' );
+		} );
+
+		// Add the 'enabled' class to the available routes
+		if( routes.left ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'enabled' );	} );
+		if( routes.right ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+		if( routes.up ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'enabled' );	} );
+		if( routes.down ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+
+		// Prev/next buttons
+		if( routes.left || routes.up ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+		if( routes.right || routes.down ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+
+		// Highlight fragment directions
+		if( currentSlide ) {
+
+			// Always apply fragment decorator to prev/next buttons
+			if( fragments.prev ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+			if( fragments.next ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+
+			// Apply fragment decorators to directional buttons based on
+			// what slide axis they are in
+			if( isVerticalSlide( currentSlide ) ) {
+				if( fragments.prev ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+				if( fragments.next ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+			}
+			else {
+				if( fragments.prev ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+				if( fragments.next ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+			}
+
+		}
+
+	}
+
+	/**
+	 * Updates the background elements to reflect the current
+	 * slide.
+	 *
+	 * @param {Boolean} includeAll If true, the backgrounds of
+	 * all vertical slides (not just the present) will be updated.
+	 */
+	function updateBackground( includeAll ) {
+
+		var currentBackground = null;
+
+		// Reverse past/future classes when in RTL mode
+		var horizontalPast = config.rtl ? 'future' : 'past',
+			horizontalFuture = config.rtl ? 'past' : 'future';
+
+		// Update the classes of all backgrounds to match the
+		// states of their slides (past/present/future)
+		toArray( dom.background.childNodes ).forEach( function( backgroundh, h ) {
+
+			backgroundh.classList.remove( 'past' );
+			backgroundh.classList.remove( 'present' );
+			backgroundh.classList.remove( 'future' );
+
+			if( h < indexh ) {
+				backgroundh.classList.add( horizontalPast );
+			}
+			else if ( h > indexh ) {
+				backgroundh.classList.add( horizontalFuture );
+			}
+			else {
+				backgroundh.classList.add( 'present' );
+
+				// Store a reference to the current background element
+				currentBackground = backgroundh;
+			}
+
+			if( includeAll || h === indexh ) {
+				toArray( backgroundh.querySelectorAll( '.slide-background' ) ).forEach( function( backgroundv, v ) {
+
+					backgroundv.classList.remove( 'past' );
+					backgroundv.classList.remove( 'present' );
+					backgroundv.classList.remove( 'future' );
+
+					if( v < indexv ) {
+						backgroundv.classList.add( 'past' );
+					}
+					else if ( v > indexv ) {
+						backgroundv.classList.add( 'future' );
+					}
+					else {
+						backgroundv.classList.add( 'present' );
+
+						// Only if this is the present horizontal and vertical slide
+						if( h === indexh ) currentBackground = backgroundv;
+					}
+
+				} );
+			}
+
+		} );
+
+		// Stop any currently playing video background
+		if( previousBackground ) {
+
+			var previousVideo = previousBackground.querySelector( 'video' );
+			if( previousVideo ) previousVideo.pause();
+
+		}
+
+		if( currentBackground ) {
+
+			// Start video playback
+			var currentVideo = currentBackground.querySelector( 'video' );
+			if( currentVideo ) {
+				if( currentVideo.currentTime > 0 ) currentVideo.currentTime = 0;
+				currentVideo.play();
+			}
+
+			var backgroundImageURL = currentBackground.style.backgroundImage || '';
+
+			// Restart GIFs (doesn't work in Firefox)
+			if( /\.gif/i.test( backgroundImageURL ) ) {
+				currentBackground.style.backgroundImage = '';
+				window.getComputedStyle( currentBackground ).opacity;
+				currentBackground.style.backgroundImage = backgroundImageURL;
+			}
+
+			// Don't transition between identical backgrounds. This
+			// prevents unwanted flicker.
+			var previousBackgroundHash = previousBackground ? previousBackground.getAttribute( 'data-background-hash' ) : null;
+			var currentBackgroundHash = currentBackground.getAttribute( 'data-background-hash' );
+			if( currentBackgroundHash && currentBackgroundHash === previousBackgroundHash && currentBackground !== previousBackground ) {
+				dom.background.classList.add( 'no-transition' );
+			}
+
+			previousBackground = currentBackground;
+
+		}
+
+		// If there's a background brightness flag for this slide,
+		// bubble it to the .reveal container
+		if( currentSlide ) {
+			[ 'has-light-background', 'has-dark-background' ].forEach( function( classToBubble ) {
+				if( currentSlide.classList.contains( classToBubble ) ) {
+					dom.wrapper.classList.add( classToBubble );
+				}
+				else {
+					dom.wrapper.classList.remove( classToBubble );
+				}
+			} );
+		}
+
+		// Allow the first background to apply without transition
+		setTimeout( function() {
+			dom.background.classList.remove( 'no-transition' );
+		}, 1 );
+
+	}
+
+	/**
+	 * Updates the position of the parallax background based
+	 * on the current slide index.
+	 */
+	function updateParallax() {
+
+		if( config.parallaxBackgroundImage ) {
+
+			var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
+				verticalSlides = dom.wrapper.querySelectorAll( VERTICAL_SLIDES_SELECTOR );
+
+			var backgroundSize = dom.background.style.backgroundSize.split( ' ' ),
+				backgroundWidth, backgroundHeight;
+
+			if( backgroundSize.length === 1 ) {
+				backgroundWidth = backgroundHeight = parseInt( backgroundSize[0], 10 );
+			}
+			else {
+				backgroundWidth = parseInt( backgroundSize[0], 10 );
+				backgroundHeight = parseInt( backgroundSize[1], 10 );
+			}
+
+			var slideWidth = dom.background.offsetWidth,
+				horizontalSlideCount = horizontalSlides.length,
+				horizontalOffsetMultiplier,
+				horizontalOffset;
+
+			if( typeof config.parallaxBackgroundHorizontal === 'number' ) {
+				horizontalOffsetMultiplier = config.parallaxBackgroundHorizontal;
+			}
+			else {
+				horizontalOffsetMultiplier = horizontalSlideCount > 1 ? ( backgroundWidth - slideWidth ) / ( horizontalSlideCount-1 ) : 0;
+			}
+
+			horizontalOffset = horizontalOffsetMultiplier * indexh * -1;
+
+			var slideHeight = dom.background.offsetHeight,
+				verticalSlideCount = verticalSlides.length,
+				verticalOffsetMultiplier,
+				verticalOffset;
+
+			if( typeof config.parallaxBackgroundVertical === 'number' ) {
+				verticalOffsetMultiplier = config.parallaxBackgroundVertical;
+			}
+			else {
+				verticalOffsetMultiplier = ( backgroundHeight - slideHeight ) / ( verticalSlideCount-1 );
+			}
+
+			verticalOffset = verticalSlideCount > 0 ?  verticalOffsetMultiplier * indexv * 1 : 0;
+
+			dom.background.style.backgroundPosition = horizontalOffset + 'px ' + -verticalOffset + 'px';
+
+		}
+
+	}
+
+	/**
+	 * Called when the given slide is within the configured view
+	 * distance. Shows the slide element and loads any content
+	 * that is set to load lazily (data-src).
+	 */
+	function showSlide( slide ) {
+
+		// Show the slide element
+		slide.style.display = 'block';
+
+		// Media elements with data-src attributes
+		toArray( slide.querySelectorAll( 'img[data-src], video[data-src], audio[data-src]' ) ).forEach( function( element ) {
+			element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
+			element.removeAttribute( 'data-src' );
+		} );
+
+		// Media elements with <source> children
+		toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( media ) {
+			var sources = 0;
+
+			toArray( media.querySelectorAll( 'source[data-src]' ) ).forEach( function( source ) {
+				source.setAttribute( 'src', source.getAttribute( 'data-src' ) );
+				source.removeAttribute( 'data-src' );
+				sources += 1;
+			} );
+
+			// If we rewrote sources for this video/audio element, we need
+			// to manually tell it to load from its new origin
+			if( sources > 0 ) {
+				media.load();
+			}
+		} );
+
+
+		// Show the corresponding background element
+		var indices = getIndices( slide );
+		var background = getSlideBackground( indices.h, indices.v );
+		if( background ) {
+			background.style.display = 'block';
+
+			// If the background contains media, load it
+			if( background.hasAttribute( 'data-loaded' ) === false ) {
+				background.setAttribute( 'data-loaded', 'true' );
+
+				var backgroundImage = slide.getAttribute( 'data-background-image' ),
+					backgroundVideo = slide.getAttribute( 'data-background-video' ),
+					backgroundVideoLoop = slide.hasAttribute( 'data-background-video-loop' ),
+					backgroundIframe = slide.getAttribute( 'data-background-iframe' );
+
+				// Images
+				if( backgroundImage ) {
+					background.style.backgroundImage = 'url('+ backgroundImage +')';
+				}
+				// Videos
+				else if ( backgroundVideo && !isSpeakerNotes() ) {
+					var video = document.createElement( 'video' );
+
+					if( backgroundVideoLoop ) {
+						video.setAttribute( 'loop', '' );
+					}
+
+					// Support comma separated lists of video sources
+					backgroundVideo.split( ',' ).forEach( function( source ) {
+						video.innerHTML += '<source src="'+ source +'">';
+					} );
+
+					background.appendChild( video );
+				}
+				// Iframes
+				else if( backgroundIframe ) {
+					var iframe = document.createElement( 'iframe' );
+						iframe.setAttribute( 'src', backgroundIframe );
+						iframe.style.width  = '100%';
+						iframe.style.height = '100%';
+						iframe.style.maxHeight = '100%';
+						iframe.style.maxWidth = '100%';
+
+					background.appendChild( iframe );
+				}
+			}
+		}
+
+	}
+
+	/**
+	 * Called when the given slide is moved outside of the
+	 * configured view distance.
+	 */
+	function hideSlide( slide ) {
+
+		// Hide the slide element
+		slide.style.display = 'none';
+
+		// Hide the corresponding background element
+		var indices = getIndices( slide );
+		var background = getSlideBackground( indices.h, indices.v );
+		if( background ) {
+			background.style.display = 'none';
+		}
+
+	}
+
+	/**
+	 * Determine what available routes there are for navigation.
+	 *
+	 * @return {Object} containing four booleans: left/right/up/down
+	 */
+	function availableRoutes() {
+
+		var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
+			verticalSlides = dom.wrapper.querySelectorAll( VERTICAL_SLIDES_SELECTOR );
+
+		var routes = {
+			left: indexh > 0 || config.loop,
+			right: indexh < horizontalSlides.length - 1 || config.loop,
+			up: indexv > 0,
+			down: indexv < verticalSlides.length - 1
+		};
+
+		// reverse horizontal controls for rtl
+		if( config.rtl ) {
+			var left = routes.left;
+			routes.left = routes.right;
+			routes.right = left;
+		}
+
+		return routes;
+
+	}
+
+	/**
+	 * Returns an object describing the available fragment
+	 * directions.
+	 *
+	 * @return {Object} two boolean properties: prev/next
+	 */
+	function availableFragments() {
+
+		if( currentSlide && config.fragments ) {
+			var fragments = currentSlide.querySelectorAll( '.fragment' );
+			var hiddenFragments = currentSlide.querySelectorAll( '.fragment:not(.visible)' );
+
+			return {
+				prev: fragments.length - hiddenFragments.length > 0,
+				next: !!hiddenFragments.length
+			};
+		}
+		else {
+			return { prev: false, next: false };
+		}
+
+	}
+
+	/**
+	 * Enforces origin-specific format rules for embedded media.
+	 */
+	function formatEmbeddedContent() {
+
+		var _appendParamToIframeSource = function( sourceAttribute, sourceURL, param ) {
+			toArray( dom.slides.querySelectorAll( 'iframe['+ sourceAttribute +'*="'+ sourceURL +'"]' ) ).forEach( function( el ) {
+				var src = el.getAttribute( sourceAttribute );
+				if( src && src.indexOf( param ) === -1 ) {
+					el.setAttribute( sourceAttribute, src + ( !/\?/.test( src ) ? '?' : '&' ) + param );
+				}
+			});
+		};
+
+		// YouTube frames must include "?enablejsapi=1"
+		_appendParamToIframeSource( 'src', 'youtube.com/embed/', 'enablejsapi=1' );
+		_appendParamToIframeSource( 'data-src', 'youtube.com/embed/', 'enablejsapi=1' );
+
+		// Vimeo frames must include "?api=1"
+		_appendParamToIframeSource( 'src', 'player.vimeo.com/', 'api=1' );
+		_appendParamToIframeSource( 'data-src', 'player.vimeo.com/', 'api=1' );
+
+	}
+
+	/**
+	 * Start playback of any embedded content inside of
+	 * the targeted slide.
+	 */
+	function startEmbeddedContent( slide ) {
+
+		if( slide && !isSpeakerNotes() ) {
+			// Restart GIFs
+			toArray( slide.querySelectorAll( 'img[src$=".gif"]' ) ).forEach( function( el ) {
+				// Setting the same unchanged source like this was confirmed
+				// to work in Chrome, FF & Safari
+				el.setAttribute( 'src', el.getAttribute( 'src' ) );
+			} );
+
+			// HTML5 media elements
+			toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
+				if( el.hasAttribute( 'data-autoplay' ) && typeof el.play === 'function' ) {
+					el.play();
+				}
+			} );
+
+			// Normal iframes
+			toArray( slide.querySelectorAll( 'iframe[src]' ) ).forEach( function( el ) {
+				startEmbeddedIframe( { target: el } );
+			} );
+
+			// Lazy loading iframes
+			toArray( slide.querySelectorAll( 'iframe[data-src]' ) ).forEach( function( el ) {
+				if( el.getAttribute( 'src' ) !== el.getAttribute( 'data-src' ) ) {
+					el.removeEventListener( 'load', startEmbeddedIframe ); // remove first to avoid dupes
+					el.addEventListener( 'load', startEmbeddedIframe );
+					el.setAttribute( 'src', el.getAttribute( 'data-src' ) );
+				}
+			} );
+		}
+
+	}
+
+	/**
+	 * "Starts" the content of an embedded iframe using the
+	 * postmessage API.
+	 */
+	function startEmbeddedIframe( event ) {
+
+		var iframe = event.target;
+
+		// YouTube postMessage API
+		if( /youtube\.com\/embed\//.test( iframe.getAttribute( 'src' ) ) && iframe.hasAttribute( 'data-autoplay' ) ) {
+			iframe.contentWindow.postMessage( '{"event":"command","func":"playVideo","args":""}', '*' );
+		}
+		// Vimeo postMessage API
+		else if( /player\.vimeo\.com\//.test( iframe.getAttribute( 'src' ) ) && iframe.hasAttribute( 'data-autoplay' ) ) {
+			iframe.contentWindow.postMessage( '{"method":"play"}', '*' );
+		}
+		// Generic postMessage API
+		else {
+			iframe.contentWindow.postMessage( 'slide:start', '*' );
+		}
+
+	}
+
+	/**
+	 * Stop playback of any embedded content inside of
+	 * the targeted slide.
+	 */
+	function stopEmbeddedContent( slide ) {
+
+		if( slide && slide.parentNode ) {
+			// HTML5 media elements
+			toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
+				if( !el.hasAttribute( 'data-ignore' ) && typeof el.pause === 'function' ) {
+					el.pause();
+				}
+			} );
+
+			// Generic postMessage API for non-lazy loaded iframes
+			toArray( slide.querySelectorAll( 'iframe' ) ).forEach( function( el ) {
+				el.contentWindow.postMessage( 'slide:stop', '*' );
+				el.removeEventListener( 'load', startEmbeddedIframe );
+			});
+
+			// YouTube postMessage API
+			toArray( slide.querySelectorAll( 'iframe[src*="youtube.com/embed/"]' ) ).forEach( function( el ) {
+				if( !el.hasAttribute( 'data-ignore' ) && typeof el.contentWindow.postMessage === 'function' ) {
+					el.contentWindow.postMessage( '{"event":"command","func":"pauseVideo","args":""}', '*' );
+				}
+			});
+
+			// Vimeo postMessage API
+			toArray( slide.querySelectorAll( 'iframe[src*="player.vimeo.com/"]' ) ).forEach( function( el ) {
+				if( !el.hasAttribute( 'data-ignore' ) && typeof el.contentWindow.postMessage === 'function' ) {
+					el.contentWindow.postMessage( '{"method":"pause"}', '*' );
+				}
+			});
+
+			// Lazy loading iframes
+			toArray( slide.querySelectorAll( 'iframe[data-src]' ) ).forEach( function( el ) {
+				// Only removing the src doesn't actually unload the frame
+				// in all browsers (Firefox) so we set it to blank first
+				el.setAttribute( 'src', 'about:blank' );
+				el.removeAttribute( 'src' );
+			} );
+		}
+
+	}
+
+	/**
+	 * Returns the number of past slides. This can be used as a global
+	 * flattened index for slides.
+	 */
+	function getSlidePastCount() {
+
+		var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
+
+		// The number of past slides
+		var pastCount = 0;
+
+		// Step through all slides and count the past ones
+		mainLoop: for( var i = 0; i < horizontalSlides.length; i++ ) {
+
+			var horizontalSlide = horizontalSlides[i];
+			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
+
+			for( var j = 0; j < verticalSlides.length; j++ ) {
+
+				// Stop as soon as we arrive at the present
+				if( verticalSlides[j].classList.contains( 'present' ) ) {
+					break mainLoop;
+				}
+
+				pastCount++;
+
+			}
+
+			// Stop as soon as we arrive at the present
+			if( horizontalSlide.classList.contains( 'present' ) ) {
+				break;
+			}
+
+			// Don't count the wrapping section for vertical slides
+			if( horizontalSlide.classList.contains( 'stack' ) === false ) {
+				pastCount++;
+			}
+
+		}
+
+		return pastCount;
+
+	}
+
+	/**
+	 * Returns a value ranging from 0-1 that represents
+	 * how far into the presentation we have navigated.
+	 */
+	function getProgress() {
+
+		// The number of past and total slides
+		var totalCount = getTotalSlides();
+		var pastCount = getSlidePastCount();
+
+		if( currentSlide ) {
+
+			var allFragments = currentSlide.querySelectorAll( '.fragment' );
+
+			// If there are fragments in the current slide those should be
+			// accounted for in the progress.
+			if( allFragments.length > 0 ) {
+				var visibleFragments = currentSlide.querySelectorAll( '.fragment.visible' );
+
+				// This value represents how big a portion of the slide progress
+				// that is made up by its fragments (0-1)
+				var fragmentWeight = 0.9;
+
+				// Add fragment progress to the past slide count
+				pastCount += ( visibleFragments.length / allFragments.length ) * fragmentWeight;
+			}
+
+		}
+
+		return pastCount / ( totalCount - 1 );
+
+	}
+
+	/**
+	 * Checks if this presentation is running inside of the
+	 * speaker notes window.
+	 */
+	function isSpeakerNotes() {
+
+		return !!window.location.search.match( /receiver/gi );
+
+	}
+
+	/**
+	 * Reads the current URL (hash) and navigates accordingly.
+	 */
+	function readURL() {
+
+		var hash = window.location.hash;
+
+		// Attempt to parse the hash as either an index or name
+		var bits = hash.slice( 2 ).split( '/' ),
+			name = hash.replace( /#|\//gi, '' );
+
+		// If the first bit is invalid and there is a name we can
+		// assume that this is a named link
+		if( isNaN( parseInt( bits[0], 10 ) ) && name.length ) {
+			var element;
+
+			// Ensure the named link is a valid HTML ID attribute
+			if( /^[a-zA-Z][\w:.-]*$/.test( name ) ) {
+				// Find the slide with the specified ID
+				element = document.getElementById( name );
+			}
+
+			if( element ) {
+				// Find the position of the named slide and navigate to it
+				var indices = Reveal.getIndices( element );
+				slide( indices.h, indices.v );
+			}
+			// If the slide doesn't exist, navigate to the current slide
+			else {
+				slide( indexh || 0, indexv || 0 );
+			}
+		}
+		else {
+			// Read the index components of the hash
+			var h = parseInt( bits[0], 10 ) || 0,
+				v = parseInt( bits[1], 10 ) || 0;
+
+			if( h !== indexh || v !== indexv ) {
+				slide( h, v );
+			}
+		}
+
+	}
+
+	/**
+	 * Updates the page URL (hash) to reflect the current
+	 * state.
+	 *
+	 * @param {Number} delay The time in ms to wait before
+	 * writing the hash
+	 */
+	function writeURL( delay ) {
+
+		if( config.history ) {
+
+			// Make sure there's never more than one timeout running
+			clearTimeout( writeURLTimeout );
+
+			// If a delay is specified, timeout this call
+			if( typeof delay === 'number' ) {
+				writeURLTimeout = setTimeout( writeURL, delay );
+			}
+			else if( currentSlide ) {
+				var url = '/';
+
+				// Attempt to create a named link based on the slide's ID
+				var id = currentSlide.getAttribute( 'id' );
+				if( id ) {
+					id = id.replace( /[^a-zA-Z0-9\-\_\:\.]/g, '' );
+				}
+
+				// If the current slide has an ID, use that as a named link
+				if( typeof id === 'string' && id.length ) {
+					url = '/' + id;
+				}
+				// Otherwise use the /h/v index
+				else {
+					if( indexh > 0 || indexv > 0 ) url += indexh;
+					if( indexv > 0 ) url += '/' + indexv;
+				}
+
+				window.location.hash = url;
+			}
+		}
+
+	}
+
+	/**
+	 * Retrieves the h/v location of the current, or specified,
+	 * slide.
+	 *
+	 * @param {HTMLElement} slide If specified, the returned
+	 * index will be for this slide rather than the currently
+	 * active one
+	 *
+	 * @return {Object} { h: <int>, v: <int>, f: <int> }
+	 */
+	function getIndices( slide ) {
+
+		// By default, return the current indices
+		var h = indexh,
+			v = indexv,
+			f;
+
+		// If a slide is specified, return the indices of that slide
+		if( slide ) {
+			var isVertical = isVerticalSlide( slide );
+			var slideh = isVertical ? slide.parentNode : slide;
+
+			// Select all horizontal slides
+			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
+
+			// Now that we know which the horizontal slide is, get its index
+			h = Math.max( horizontalSlides.indexOf( slideh ), 0 );
+
+			// Assume we're not vertical
+			v = undefined;
+
+			// If this is a vertical slide, grab the vertical index
+			if( isVertical ) {
+				v = Math.max( toArray( slide.parentNode.querySelectorAll( 'section' ) ).indexOf( slide ), 0 );
+			}
+		}
+
+		if( !slide && currentSlide ) {
+			var hasFragments = currentSlide.querySelectorAll( '.fragment' ).length > 0;
+			if( hasFragments ) {
+				var currentFragment = currentSlide.querySelector( '.current-fragment' );
+				if( currentFragment && currentFragment.hasAttribute( 'data-fragment-index' ) ) {
+					f = parseInt( currentFragment.getAttribute( 'data-fragment-index' ), 10 );
+				}
+				else {
+					f = currentSlide.querySelectorAll( '.fragment.visible' ).length - 1;
+				}
+			}
+		}
+
+		return { h: h, v: v, f: f };
+
+	}
+
+	/**
+	 * Retrieves the total number of slides in this presentation.
+	 */
+	function getTotalSlides() {
+
+		return dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ).length;
+
+	}
+
+	/**
+	 * Returns the slide element matching the specified index.
+	 */
+	function getSlide( x, y ) {
+
+		var horizontalSlide = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR )[ x ];
+		var verticalSlides = horizontalSlide && horizontalSlide.querySelectorAll( 'section' );
+
+		if( verticalSlides && verticalSlides.length && typeof y === 'number' ) {
+			return verticalSlides ? verticalSlides[ y ] : undefined;
+		}
+
+		return horizontalSlide;
+
+	}
+
+	/**
+	 * Returns the background element for the given slide.
+	 * All slides, even the ones with no background properties
+	 * defined, have a background element so as long as the
+	 * index is valid an element will be returned.
+	 */
+	function getSlideBackground( x, y ) {
+
+		// When printing to PDF the slide backgrounds are nested
+		// inside of the slides
+		if( isPrintingPDF() ) {
+			var slide = getSlide( x, y );
+			if( slide ) {
+				var background = slide.querySelector( '.slide-background' );
+				if( background && background.parentNode === slide ) {
+					return background;
+				}
+			}
+
+			return undefined;
+		}
+
+		var horizontalBackground = dom.wrapper.querySelectorAll( '.backgrounds>.slide-background' )[ x ];
+		var verticalBackgrounds = horizontalBackground && horizontalBackground.querySelectorAll( '.slide-background' );
+
+		if( verticalBackgrounds && verticalBackgrounds.length && typeof y === 'number' ) {
+			return verticalBackgrounds ? verticalBackgrounds[ y ] : undefined;
+		}
+
+		return horizontalBackground;
+
+	}
+
+	/**
+	 * Retrieves the speaker notes from a slide. Notes can be
+	 * defined in two ways:
+	 * 1. As a data-notes attribute on the slide <section>
+	 * 2. As an <aside class="notes"> inside of the slide
+	 */
+	function getSlideNotes( slide ) {
+
+		// Default to the current slide
+		slide = slide || currentSlide;
+
+		// Notes can be specified via the data-notes attribute...
+		if( slide.hasAttribute( 'data-notes' ) ) {
+			return slide.getAttribute( 'data-notes' );
+		}
+
+		// ... or using an <aside class="notes"> element
+		var notesElement = slide.querySelector( 'aside.notes' );
+		if( notesElement ) {
+			return notesElement.innerHTML;
+		}
+
+		return null;
+
+	}
+
+	/**
+	 * Retrieves the current state of the presentation as
+	 * an object. This state can then be restored at any
+	 * time.
+	 */
+	function getState() {
+
+		var indices = getIndices();
+
+		return {
+			indexh: indices.h,
+			indexv: indices.v,
+			indexf: indices.f,
+			paused: isPaused(),
+			overview: isOverview()
+		};
+
+	}
+
+	/**
+	 * Restores the presentation to the given state.
+	 *
+	 * @param {Object} state As generated by getState()
+	 */
+	function setState( state ) {
+
+		if( typeof state === 'object' ) {
+			slide( deserialize( state.indexh ), deserialize( state.indexv ), deserialize( state.indexf ) );
+
+			var pausedFlag = deserialize( state.paused ),
+				overviewFlag = deserialize( state.overview );
+
+			if( typeof pausedFlag === 'boolean' && pausedFlag !== isPaused() ) {
+				togglePause( pausedFlag );
+			}
+
+			if( typeof overviewFlag === 'boolean' && overviewFlag !== isOverview() ) {
+				toggleOverview( overviewFlag );
+			}
+		}
+
+	}
+
+	/**
+	 * Return a sorted fragments list, ordered by an increasing
+	 * "data-fragment-index" attribute.
+	 *
+	 * Fragments will be revealed in the order that they are returned by
+	 * this function, so you can use the index attributes to control the
+	 * order of fragment appearance.
+	 *
+	 * To maintain a sensible default fragment order, fragments are presumed
+	 * to be passed in document order. This function adds a "fragment-index"
+	 * attribute to each node if such an attribute is not already present,
+	 * and sets that attribute to an integer value which is the position of
+	 * the fragment within the fragments list.
+	 */
+	function sortFragments( fragments ) {
+
+		fragments = toArray( fragments );
+
+		var ordered = [],
+			unordered = [],
+			sorted = [];
+
+		// Group ordered and unordered elements
+		fragments.forEach( function( fragment, i ) {
+			if( fragment.hasAttribute( 'data-fragment-index' ) ) {
+				var index = parseInt( fragment.getAttribute( 'data-fragment-index' ), 10 );
+
+				if( !ordered[index] ) {
+					ordered[index] = [];
+				}
+
+				ordered[index].push( fragment );
+			}
+			else {
+				unordered.push( [ fragment ] );
+			}
+		} );
+
+		// Append fragments without explicit indices in their
+		// DOM order
+		ordered = ordered.concat( unordered );
+
+		// Manually count the index up per group to ensure there
+		// are no gaps
+		var index = 0;
+
+		// Push all fragments in their sorted order to an array,
+		// this flattens the groups
+		ordered.forEach( function( group ) {
+			group.forEach( function( fragment ) {
+				sorted.push( fragment );
+				fragment.setAttribute( 'data-fragment-index', index );
+			} );
+
+			index ++;
+		} );
+
+		return sorted;
+
+	}
+
+	/**
+	 * Navigate to the specified slide fragment.
+	 *
+	 * @param {Number} index The index of the fragment that
+	 * should be shown, -1 means all are invisible
+	 * @param {Number} offset Integer offset to apply to the
+	 * fragment index
+	 *
+	 * @return {Boolean} true if a change was made in any
+	 * fragments visibility as part of this call
+	 */
+	function navigateFragment( index, offset ) {
+
+		if( currentSlide && config.fragments ) {
+
+			var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment' ) );
+			if( fragments.length ) {
+
+				// If no index is specified, find the current
+				if( typeof index !== 'number' ) {
+					var lastVisibleFragment = sortFragments( currentSlide.querySelectorAll( '.fragment.visible' ) ).pop();
+
+					if( lastVisibleFragment ) {
+						index = parseInt( lastVisibleFragment.getAttribute( 'data-fragment-index' ) || 0, 10 );
+					}
+					else {
+						index = -1;
+					}
+				}
+
+				// If an offset is specified, apply it to the index
+				if( typeof offset === 'number' ) {
+					index += offset;
+				}
+
+				var fragmentsShown = [],
+					fragmentsHidden = [];
+
+				toArray( fragments ).forEach( function( element, i ) {
+
+					if( element.hasAttribute( 'data-fragment-index' ) ) {
+						i = parseInt( element.getAttribute( 'data-fragment-index' ), 10 );
+					}
+
+					// Visible fragments
+					if( i <= index ) {
+						if( !element.classList.contains( 'visible' ) ) fragmentsShown.push( element );
+						element.classList.add( 'visible' );
+						element.classList.remove( 'current-fragment' );
+
+						// Announce the fragments one by one to the Screen Reader
+						dom.statusDiv.textContent = element.textContent;
+
+						if( i === index ) {
+							element.classList.add( 'current-fragment' );
+						}
+					}
+					// Hidden fragments
+					else {
+						if( element.classList.contains( 'visible' ) ) fragmentsHidden.push( element );
+						element.classList.remove( 'visible' );
+						element.classList.remove( 'current-fragment' );
+					}
+
+
+				} );
+
+				if( fragmentsHidden.length ) {
+					dispatchEvent( 'fragmenthidden', { fragment: fragmentsHidden[0], fragments: fragmentsHidden } );
+				}
+
+				if( fragmentsShown.length ) {
+					dispatchEvent( 'fragmentshown', { fragment: fragmentsShown[0], fragments: fragmentsShown } );
+				}
+
+				updateControls();
+				updateProgress();
+
+				return !!( fragmentsShown.length || fragmentsHidden.length );
+
+			}
+
+		}
+
+		return false;
+
+	}
+
+	/**
+	 * Navigate to the next slide fragment.
+	 *
+	 * @return {Boolean} true if there was a next fragment,
+	 * false otherwise
+	 */
+	function nextFragment() {
+
+		return navigateFragment( null, 1 );
+
+	}
+
+	/**
+	 * Navigate to the previous slide fragment.
+	 *
+	 * @return {Boolean} true if there was a previous fragment,
+	 * false otherwise
+	 */
+	function previousFragment() {
+
+		return navigateFragment( null, -1 );
+
+	}
+
+	/**
+	 * Cues a new automated slide if enabled in the config.
+	 */
+	function cueAutoSlide() {
+
+		cancelAutoSlide();
+
+		if( currentSlide ) {
+
+			var currentFragment = currentSlide.querySelector( '.current-fragment' );
+
+			var fragmentAutoSlide = currentFragment ? currentFragment.getAttribute( 'data-autoslide' ) : null;
+			var parentAutoSlide = currentSlide.parentNode ? currentSlide.parentNode.getAttribute( 'data-autoslide' ) : null;
+			var slideAutoSlide = currentSlide.getAttribute( 'data-autoslide' );
+
+			// Pick value in the following priority order:
+			// 1. Current fragment's data-autoslide
+			// 2. Current slide's data-autoslide
+			// 3. Parent slide's data-autoslide
+			// 4. Global autoSlide setting
+			if( fragmentAutoSlide ) {
+				autoSlide = parseInt( fragmentAutoSlide, 10 );
+			}
+			else if( slideAutoSlide ) {
+				autoSlide = parseInt( slideAutoSlide, 10 );
+			}
+			else if( parentAutoSlide ) {
+				autoSlide = parseInt( parentAutoSlide, 10 );
+			}
+			else {
+				autoSlide = config.autoSlide;
+			}
+
+			// If there are media elements with data-autoplay,
+			// automatically set the autoSlide duration to the
+			// length of that media. Not applicable if the slide
+			// is divided up into fragments.
+			if( currentSlide.querySelectorAll( '.fragment' ).length === 0 ) {
+				toArray( currentSlide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
+					if( el.hasAttribute( 'data-autoplay' ) ) {
+						if( autoSlide && el.duration * 1000 > autoSlide ) {
+							autoSlide = ( el.duration * 1000 ) + 1000;
+						}
+					}
+				} );
+			}
+
+			// Cue the next auto-slide if:
+			// - There is an autoSlide value
+			// - Auto-sliding isn't paused by the user
+			// - The presentation isn't paused
+			// - The overview isn't active
+			// - The presentation isn't over
+			if( autoSlide && !autoSlidePaused && !isPaused() && !isOverview() && ( !Reveal.isLastSlide() || availableFragments().next || config.loop === true ) ) {
+				autoSlideTimeout = setTimeout( navigateNext, autoSlide );
+				autoSlideStartTime = Date.now();
+			}
+
+			if( autoSlidePlayer ) {
+				autoSlidePlayer.setPlaying( autoSlideTimeout !== -1 );
+			}
+
+		}
+
+	}
+
+	/**
+	 * Cancels any ongoing request to auto-slide.
+	 */
+	function cancelAutoSlide() {
+
+		clearTimeout( autoSlideTimeout );
+		autoSlideTimeout = -1;
+
+	}
+
+	function pauseAutoSlide() {
+
+		if( autoSlide && !autoSlidePaused ) {
+			autoSlidePaused = true;
+			dispatchEvent( 'autoslidepaused' );
+			clearTimeout( autoSlideTimeout );
+
+			if( autoSlidePlayer ) {
+				autoSlidePlayer.setPlaying( false );
+			}
+		}
+
+	}
+
+	function resumeAutoSlide() {
+
+		if( autoSlide && autoSlidePaused ) {
+			autoSlidePaused = false;
+			dispatchEvent( 'autoslideresumed' );
+			cueAutoSlide();
+		}
+
+	}
+
+	function navigateLeft() {
+
+		// Reverse for RTL
+		if( config.rtl ) {
+			if( ( isOverview() || nextFragment() === false ) && availableRoutes().left ) {
+				slide( indexh + 1 );
+			}
+		}
+		// Normal navigation
+		else if( ( isOverview() || previousFragment() === false ) && availableRoutes().left ) {
+			slide( indexh - 1 );
+		}
+
+	}
+
+	function navigateRight() {
+
+		// Reverse for RTL
+		if( config.rtl ) {
+			if( ( isOverview() || previousFragment() === false ) && availableRoutes().right ) {
+				slide( indexh - 1 );
+			}
+		}
+		// Normal navigation
+		else if( ( isOverview() || nextFragment() === false ) && availableRoutes().right ) {
+			slide( indexh + 1 );
+		}
+
+	}
+
+	function navigateUp() {
+
+		// Prioritize hiding fragments
+		if( ( isOverview() || previousFragment() === false ) && availableRoutes().up ) {
+			slide( indexh, indexv - 1 );
+		}
+
+	}
+
+	function navigateDown() {
+
+		// Prioritize revealing fragments
+		if( ( isOverview() || nextFragment() === false ) && availableRoutes().down ) {
+			slide( indexh, indexv + 1 );
+		}
+
+	}
+
+	/**
+	 * Navigates backwards, prioritized in the following order:
+	 * 1) Previous fragment
+	 * 2) Previous vertical slide
+	 * 3) Previous horizontal slide
+	 */
+	function navigatePrev() {
+
+		// Prioritize revealing fragments
+		if( previousFragment() === false ) {
+			if( availableRoutes().up ) {
+				navigateUp();
+			}
+			else {
+				// Fetch the previous horizontal slide, if there is one
+				var previousSlide;
+
+				if( config.rtl ) {
+					previousSlide = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.future' ) ).pop();
+				}
+				else {
+					previousSlide = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.past' ) ).pop();
+				}
+
+				if( previousSlide ) {
+					var v = ( previousSlide.querySelectorAll( 'section' ).length - 1 ) || undefined;
+					var h = indexh - 1;
+					slide( h, v );
+				}
+			}
+		}
+
+	}
+
+	/**
+	 * The reverse of #navigatePrev().
+	 */
+	function navigateNext() {
+
+		// Prioritize revealing fragments
+		if( nextFragment() === false ) {
+			if( availableRoutes().down ) {
+				navigateDown();
+			}
+			else if( config.rtl ) {
+				navigateLeft();
+			}
+			else {
+				navigateRight();
+			}
+		}
+
+		// If auto-sliding is enabled we need to cue up
+		// another timeout
+		cueAutoSlide();
+
+	}
+
+	/**
+	 * Checks if the target element prevents the triggering of
+	 * swipe navigation.
+	 */
+	function isSwipePrevented( target ) {
+
+		while( target && typeof target.hasAttribute === 'function' ) {
+			if( target.hasAttribute( 'data-prevent-swipe' ) ) return true;
+			target = target.parentNode;
+		}
+
+		return false;
+
+	}
+
+
+	// --------------------------------------------------------------------//
+	// ----------------------------- EVENTS -------------------------------//
+	// --------------------------------------------------------------------//
+
+	/**
+	 * Called by all event handlers that are based on user
+	 * input.
+	 */
+	function onUserInput( event ) {
+
+		if( config.autoSlideStoppable ) {
+			pauseAutoSlide();
+		}
+
+	}
+
+	/**
+	 * Handler for the document level 'keypress' event.
+	 */
+	function onDocumentKeyPress( event ) {
+
+		// Check if the pressed key is question mark
+		if( event.shiftKey && event.charCode === 63 ) {
+			if( dom.overlay ) {
+				closeOverlay();
+			}
+			else {
+				showHelp( true );
+			}
+		}
+
+	}
+
+	/**
+	 * Handler for the document level 'keydown' event.
+	 */
+	function onDocumentKeyDown( event ) {
+
+		// If there's a condition specified and it returns false,
+		// ignore this event
+		if( typeof config.keyboardCondition === 'function' && config.keyboardCondition() === false ) {
+			return true;
+		}
+
+		// Remember if auto-sliding was paused so we can toggle it
+		var autoSlideWasPaused = autoSlidePaused;
+
+		onUserInput( event );
+
+		// Check if there's a focused element that could be using
+		// the keyboard
+		var activeElementIsCE = document.activeElement && document.activeElement.contentEditable !== 'inherit';
+		var activeElementIsInput = document.activeElement && document.activeElement.tagName && /input|textarea/i.test( document.activeElement.tagName );
+
+		// Disregard the event if there's a focused element or a
+		// keyboard modifier key is present
+		if( activeElementIsCE || activeElementIsInput || (event.shiftKey && event.keyCode !== 32) || event.altKey || event.ctrlKey || event.metaKey ) return;
+
+		// While paused only allow resume keyboard events; 'b', '.''
+		var resumeKeyCodes = [66,190,191];
+		var key;
+
+		// Custom key bindings for togglePause should be able to resume
+		if( typeof config.keyboard === 'object' ) {
+			for( key in config.keyboard ) {
+				if( config.keyboard[key] === 'togglePause' ) {
+					resumeKeyCodes.push( parseInt( key, 10 ) );
+				}
+			}
+		}
+
+		if( isPaused() && resumeKeyCodes.indexOf( event.keyCode ) === -1 ) {
+			return false;
+		}
+
+		var triggered = false;
+
+		// 1. User defined key bindings
+		if( typeof config.keyboard === 'object' ) {
+
+			for( key in config.keyboard ) {
+
+				// Check if this binding matches the pressed key
+				if( parseInt( key, 10 ) === event.keyCode ) {
+
+					var value = config.keyboard[ key ];
+
+					// Callback function
+					if( typeof value === 'function' ) {
+						value.apply( null, [ event ] );
+					}
+					// String shortcuts to reveal.js API
+					else if( typeof value === 'string' && typeof Reveal[ value ] === 'function' ) {
+						Reveal[ value ].call();
+					}
+
+					triggered = true;
+
+				}
+
+			}
+
+		}
+
+		// 2. System defined key bindings
+		if( triggered === false ) {
+
+			// Assume true and try to prove false
+			triggered = true;
+
+			switch( event.keyCode ) {
+				// p, page up
+				case 80: case 33: navigatePrev(); break;
+				// n, page down
+				case 78: case 34: navigateNext(); break;
+				// h, left
+				case 72: case 37: navigateLeft(); break;
+				// l, right
+				case 76: case 39: navigateRight(); break;
+				// k, up
+				case 75: case 38: navigateUp(); break;
+				// j, down
+				case 74: case 40: navigateDown(); break;
+				// home
+				case 36: slide( 0 ); break;
+				// end
+				case 35: slide( Number.MAX_VALUE ); break;
+				// space
+				case 32: isOverview() ? deactivateOverview() : event.shiftKey ? navigatePrev() : navigateNext(); break;
+				// return
+				case 13: isOverview() ? deactivateOverview() : triggered = false; break;
+				// two-spot, semicolon, b, period, Logitech presenter tools "black screen" button
+				case 58: case 59: case 66: case 190: case 191: togglePause(); break;
+				// f
+				case 70: enterFullscreen(); break;
+				// a
+				case 65: if ( config.autoSlideStoppable ) toggleAutoSlide( autoSlideWasPaused ); break;
+				default:
+					triggered = false;
+			}
+
+		}
+
+		// If the input resulted in a triggered action we should prevent
+		// the browsers default behavior
+		if( triggered ) {
+			event.preventDefault && event.preventDefault();
+		}
+		// ESC or O key
+		else if ( ( event.keyCode === 27 || event.keyCode === 79 ) && features.transforms3d ) {
+			if( dom.overlay ) {
+				closeOverlay();
+			}
+			else {
+				toggleOverview();
+			}
+
+			event.preventDefault && event.preventDefault();
+		}
+
+		// If auto-sliding is enabled we need to cue up
+		// another timeout
+		cueAutoSlide();
+
+	}
+
+	/**
+	 * Handler for the 'touchstart' event, enables support for
+	 * swipe and pinch gestures.
+	 */
+	function onTouchStart( event ) {
+
+		if( isSwipePrevented( event.target ) ) return true;
+
+		touch.startX = event.touches[0].clientX;
+		touch.startY = event.touches[0].clientY;
+		touch.startCount = event.touches.length;
+
+		// If there's two touches we need to memorize the distance
+		// between those two points to detect pinching
+		if( event.touches.length === 2 && config.overview ) {
+			touch.startSpan = distanceBetween( {
+				x: event.touches[1].clientX,
+				y: event.touches[1].clientY
+			}, {
+				x: touch.startX,
+				y: touch.startY
+			} );
+		}
+
+	}
+
+	/**
+	 * Handler for the 'touchmove' event.
+	 */
+	function onTouchMove( event ) {
+
+		if( isSwipePrevented( event.target ) ) return true;
+
+		// Each touch should only trigger one action
+		if( !touch.captured ) {
+			onUserInput( event );
+
+			var currentX = event.touches[0].clientX;
+			var currentY = event.touches[0].clientY;
+
+			// If the touch started with two points and still has
+			// two active touches; test for the pinch gesture
+			if( event.touches.length === 2 && touch.startCount === 2 && config.overview ) {
+
+				// The current distance in pixels between the two touch points
+				var currentSpan = distanceBetween( {
+					x: event.touches[1].clientX,
+					y: event.touches[1].clientY
+				}, {
+					x: touch.startX,
+					y: touch.startY
+				} );
+
+				// If the span is larger than the desire amount we've got
+				// ourselves a pinch
+				if( Math.abs( touch.startSpan - currentSpan ) > touch.threshold ) {
+					touch.captured = true;
+
+					if( currentSpan < touch.startSpan ) {
+						activateOverview();
+					}
+					else {
+						deactivateOverview();
+					}
+				}
+
+				event.preventDefault();
+
+			}
+			// There was only one touch point, look for a swipe
+			else if( event.touches.length === 1 && touch.startCount !== 2 ) {
+
+				var deltaX = currentX - touch.startX,
+					deltaY = currentY - touch.startY;
+
+				if( deltaX > touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
+					touch.captured = true;
+					navigateLeft();
+				}
+				else if( deltaX < -touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
+					touch.captured = true;
+					navigateRight();
+				}
+				else if( deltaY > touch.threshold ) {
+					touch.captured = true;
+					navigateUp();
+				}
+				else if( deltaY < -touch.threshold ) {
+					touch.captured = true;
+					navigateDown();
+				}
+
+				// If we're embedded, only block touch events if they have
+				// triggered an action
+				if( config.embedded ) {
+					if( touch.captured || isVerticalSlide( currentSlide ) ) {
+						event.preventDefault();
+					}
+				}
+				// Not embedded? Block them all to avoid needless tossing
+				// around of the viewport in iOS
+				else {
+					event.preventDefault();
+				}
+
+			}
+		}
+		// There's a bug with swiping on some Android devices unless
+		// the default action is always prevented
+		else if( navigator.userAgent.match( /android/gi ) ) {
+			event.preventDefault();
+		}
+
+	}
+
+	/**
+	 * Handler for the 'touchend' event.
+	 */
+	function onTouchEnd( event ) {
+
+		touch.captured = false;
+
+	}
+
+	/**
+	 * Convert pointer down to touch start.
+	 */
+	function onPointerDown( event ) {
+
+		if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" ) {
+			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
+			onTouchStart( event );
+		}
+
+	}
+
+	/**
+	 * Convert pointer move to touch move.
+	 */
+	function onPointerMove( event ) {
+
+		if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" )  {
+			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
+			onTouchMove( event );
+		}
+
+	}
+
+	/**
+	 * Convert pointer up to touch end.
+	 */
+	function onPointerUp( event ) {
+
+		if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" )  {
+			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
+			onTouchEnd( event );
+		}
+
+	}
+
+	/**
+	 * Handles mouse wheel scrolling, throttled to avoid skipping
+	 * multiple slides.
+	 */
+	function onDocumentMouseScroll( event ) {
+
+		if( Date.now() - lastMouseWheelStep > 600 ) {
+
+			lastMouseWheelStep = Date.now();
+
+			var delta = event.detail || -event.wheelDelta;
+			if( delta > 0 ) {
+				navigateNext();
+			}
+			else {
+				navigatePrev();
+			}
+
+		}
+
+	}
+
+	/**
+	 * Clicking on the progress bar results in a navigation to the
+	 * closest approximate horizontal slide using this equation:
+	 *
+	 * ( clickX / presentationWidth ) * numberOfSlides
+	 */
+	function onProgressClicked( event ) {
+
+		onUserInput( event );
+
+		event.preventDefault();
+
+		var slidesTotal = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).length;
+		var slideIndex = Math.floor( ( event.clientX / dom.wrapper.offsetWidth ) * slidesTotal );
+
+		if( config.rtl ) {
+			slideIndex = slidesTotal - slideIndex;
+		}
+
+		slide( slideIndex );
+
+	}
+
+	/**
+	 * Event handler for navigation control buttons.
+	 */
+	function onNavigateLeftClicked( event ) { event.preventDefault(); onUserInput(); navigateLeft(); }
+	function onNavigateRightClicked( event ) { event.preventDefault(); onUserInput(); navigateRight(); }
+	function onNavigateUpClicked( event ) { event.preventDefault(); onUserInput(); navigateUp(); }
+	function onNavigateDownClicked( event ) { event.preventDefault(); onUserInput(); navigateDown(); }
+	function onNavigatePrevClicked( event ) { event.preventDefault(); onUserInput(); navigatePrev(); }
+	function onNavigateNextClicked( event ) { event.preventDefault(); onUserInput(); navigateNext(); }
+
+	/**
+	 * Handler for the window level 'hashchange' event.
+	 */
+	function onWindowHashChange( event ) {
+
+		readURL();
+
+	}
+
+	/**
+	 * Handler for the window level 'resize' event.
+	 */
+	function onWindowResize( event ) {
+
+		layout();
+
+	}
+
+	/**
+	 * Handle for the window level 'visibilitychange' event.
+	 */
+	function onPageVisibilityChange( event ) {
+
+		var isHidden =  document.webkitHidden ||
+						document.msHidden ||
+						document.hidden;
+
+		// If, after clicking a link or similar and we're coming back,
+		// focus the document.body to ensure we can use keyboard shortcuts
+		if( isHidden === false && document.activeElement !== document.body ) {
+			// Not all elements support .blur() - SVGs among them.
+			if( typeof document.activeElement.blur === 'function' ) {
+				document.activeElement.blur();
+			}
+			document.body.focus();
+		}
+
+	}
+
+	/**
+	 * Invoked when a slide is and we're in the overview.
+	 */
+	function onOverviewSlideClicked( event ) {
+
+		// TODO There's a bug here where the event listeners are not
+		// removed after deactivating the overview.
+		if( eventsAreBound && isOverview() ) {
+			event.preventDefault();
+
+			var element = event.target;
+
+			while( element && !element.nodeName.match( /section/gi ) ) {
+				element = element.parentNode;
+			}
+
+			if( element && !element.classList.contains( 'disabled' ) ) {
+
+				deactivateOverview();
+
+				if( element.nodeName.match( /section/gi ) ) {
+					var h = parseInt( element.getAttribute( 'data-index-h' ), 10 ),
+						v = parseInt( element.getAttribute( 'data-index-v' ), 10 );
+
+					slide( h, v );
+				}
+
+			}
+		}
+
+	}
+
+	/**
+	 * Handles clicks on links that are set to preview in the
+	 * iframe overlay.
+	 */
+	function onPreviewLinkClicked( event ) {
+
+		if( event.currentTarget && event.currentTarget.hasAttribute( 'href' ) ) {
+			var url = event.currentTarget.getAttribute( 'href' );
+			if( url ) {
+				showPreview( url );
+				event.preventDefault();
+			}
+		}
+
+	}
+
+	/**
+	 * Handles click on the auto-sliding controls element.
+	 */
+	function onAutoSlidePlayerClick( event ) {
+
+		// Replay
+		if( Reveal.isLastSlide() && config.loop === false ) {
+			slide( 0, 0 );
+			resumeAutoSlide();
+		}
+		// Resume
+		else if( autoSlidePaused ) {
+			resumeAutoSlide();
+		}
+		// Pause
+		else {
+			pauseAutoSlide();
+		}
+
+	}
+
+
+	// --------------------------------------------------------------------//
+	// ------------------------ PLAYBACK COMPONENT ------------------------//
+	// --------------------------------------------------------------------//
+
+
+	/**
+	 * Constructor for the playback component, which displays
+	 * play/pause/progress controls.
+	 *
+	 * @param {HTMLElement} container The component will append
+	 * itself to this
+	 * @param {Function} progressCheck A method which will be
+	 * called frequently to get the current progress on a range
+	 * of 0-1
+	 */
+	function Playback( container, progressCheck ) {
+
+		// Cosmetics
+		this.diameter = 50;
+		this.thickness = 3;
+
+		// Flags if we are currently playing
+		this.playing = false;
+
+		// Current progress on a 0-1 range
+		this.progress = 0;
+
+		// Used to loop the animation smoothly
+		this.progressOffset = 1;
+
+		this.container = container;
+		this.progressCheck = progressCheck;
+
+		this.canvas = document.createElement( 'canvas' );
+		this.canvas.className = 'playback';
+		this.canvas.width = this.diameter;
+		this.canvas.height = this.diameter;
+		this.context = this.canvas.getContext( '2d' );
+
+		this.container.appendChild( this.canvas );
+
+		this.render();
+
+	}
+
+	Playback.prototype.setPlaying = function( value ) {
+
+		var wasPlaying = this.playing;
+
+		this.playing = value;
+
+		// Start repainting if we weren't already
+		if( !wasPlaying && this.playing ) {
+			this.animate();
+		}
+		else {
+			this.render();
+		}
+
+	};
+
+	Playback.prototype.animate = function() {
+
+		var progressBefore = this.progress;
+
+		this.progress = this.progressCheck();
+
+		// When we loop, offset the progress so that it eases
+		// smoothly rather than immediately resetting
+		if( progressBefore > 0.8 && this.progress < 0.2 ) {
+			this.progressOffset = this.progress;
+		}
+
+		this.render();
+
+		if( this.playing ) {
+			features.requestAnimationFrameMethod.call( window, this.animate.bind( this ) );
+		}
+
+	};
+
+	/**
+	 * Renders the current progress and playback state.
+	 */
+	Playback.prototype.render = function() {
+
+		var progress = this.playing ? this.progress : 0,
+			radius = ( this.diameter / 2 ) - this.thickness,
+			x = this.diameter / 2,
+			y = this.diameter / 2,
+			iconSize = 14;
+
+		// Ease towards 1
+		this.progressOffset += ( 1 - this.progressOffset ) * 0.1;
+
+		var endAngle = ( - Math.PI / 2 ) + ( progress * ( Math.PI * 2 ) );
+		var startAngle = ( - Math.PI / 2 ) + ( this.progressOffset * ( Math.PI * 2 ) );
+
+		this.context.save();
+		this.context.clearRect( 0, 0, this.diameter, this.diameter );
+
+		// Solid background color
+		this.context.beginPath();
+		this.context.arc( x, y, radius + 2, 0, Math.PI * 2, false );
+		this.context.fillStyle = 'rgba( 0, 0, 0, 0.4 )';
+		this.context.fill();
+
+		// Draw progress track
+		this.context.beginPath();
+		this.context.arc( x, y, radius, 0, Math.PI * 2, false );
+		this.context.lineWidth = this.thickness;
+		this.context.strokeStyle = '#666';
+		this.context.stroke();
+
+		if( this.playing ) {
+			// Draw progress on top of track
+			this.context.beginPath();
+			this.context.arc( x, y, radius, startAngle, endAngle, false );
+			this.context.lineWidth = this.thickness;
+			this.context.strokeStyle = '#fff';
+			this.context.stroke();
+		}
+
+		this.context.translate( x - ( iconSize / 2 ), y - ( iconSize / 2 ) );
+
+		// Draw play/pause icons
+		if( this.playing ) {
+			this.context.fillStyle = '#fff';
+			this.context.fillRect( 0, 0, iconSize / 2 - 2, iconSize );
+			this.context.fillRect( iconSize / 2 + 2, 0, iconSize / 2 - 2, iconSize );
+		}
+		else {
+			this.context.beginPath();
+			this.context.translate( 2, 0 );
+			this.context.moveTo( 0, 0 );
+			this.context.lineTo( iconSize - 2, iconSize / 2 );
+			this.context.lineTo( 0, iconSize );
+			this.context.fillStyle = '#fff';
+			this.context.fill();
+		}
+
+		this.context.restore();
+
+	};
+
+	Playback.prototype.on = function( type, listener ) {
+		this.canvas.addEventListener( type, listener, false );
+	};
+
+	Playback.prototype.off = function( type, listener ) {
+		this.canvas.removeEventListener( type, listener, false );
+	};
+
+	Playback.prototype.destroy = function() {
+
+		this.playing = false;
+
+		if( this.canvas.parentNode ) {
+			this.container.removeChild( this.canvas );
+		}
+
+	};
+
+
+	// --------------------------------------------------------------------//
+	// ------------------------------- API --------------------------------//
+	// --------------------------------------------------------------------//
+
+
+	Reveal = {
+		initialize: initialize,
+		configure: configure,
+		sync: sync,
+
+		// Navigation methods
+		slide: slide,
+		left: navigateLeft,
+		right: navigateRight,
+		up: navigateUp,
+		down: navigateDown,
+		prev: navigatePrev,
+		next: navigateNext,
+
+		// Fragment methods
+		navigateFragment: navigateFragment,
+		prevFragment: previousFragment,
+		nextFragment: nextFragment,
+
+		// Deprecated aliases
+		navigateTo: slide,
+		navigateLeft: navigateLeft,
+		navigateRight: navigateRight,
+		navigateUp: navigateUp,
+		navigateDown: navigateDown,
+		navigatePrev: navigatePrev,
+		navigateNext: navigateNext,
+
+		// Forces an update in slide layout
+		layout: layout,
+
+		// Returns an object with the available routes as booleans (left/right/top/bottom)
+		availableRoutes: availableRoutes,
+
+		// Returns an object with the available fragments as booleans (prev/next)
+		availableFragments: availableFragments,
+
+		// Toggles the overview mode on/off
+		toggleOverview: toggleOverview,
+
+		// Toggles the "black screen" mode on/off
+		togglePause: togglePause,
+
+		// Toggles the auto slide mode on/off
+		toggleAutoSlide: toggleAutoSlide,
+
+		// State checks
+		isOverview: isOverview,
+		isPaused: isPaused,
+		isAutoSliding: isAutoSliding,
+
+		// Adds or removes all internal event listeners (such as keyboard)
+		addEventListeners: addEventListeners,
+		removeEventListeners: removeEventListeners,
+
+		// Facility for persisting and restoring the presentation state
+		getState: getState,
+		setState: setState,
+
+		// Presentation progress on range of 0-1
+		getProgress: getProgress,
+
+		// Returns the indices of the current, or specified, slide
+		getIndices: getIndices,
+
+		getTotalSlides: getTotalSlides,
+
+		// Returns the slide element at the specified index
+		getSlide: getSlide,
+
+		// Returns the slide background element at the specified index
+		getSlideBackground: getSlideBackground,
+
+		// Returns the speaker notes string for a slide, or null
+		getSlideNotes: getSlideNotes,
+
+		// Returns the previous slide element, may be null
+		getPreviousSlide: function() {
+			return previousSlide;
+		},
+
+		// Returns the current slide element
+		getCurrentSlide: function() {
+			return currentSlide;
+		},
+
+		// Returns the current scale of the presentation content
+		getScale: function() {
+			return scale;
+		},
+
+		// Returns the current configuration object
+		getConfig: function() {
+			return config;
+		},
+
+		// Helper method, retrieves query string as a key/value hash
+		getQueryHash: function() {
+			var query = {};
+
+			location.search.replace( /[A-Z0-9]+?=([\w\.%-]*)/gi, function(a) {
+				query[ a.split( '=' ).shift() ] = a.split( '=' ).pop();
+			} );
+
+			// Basic deserialization
+			for( var i in query ) {
+				var value = query[ i ];
+
+				query[ i ] = deserialize( unescape( value ) );
+			}
+
+			return query;
+		},
+
+		// Returns true if we're currently on the first slide
+		isFirstSlide: function() {
+			return ( indexh === 0 && indexv === 0 );
+		},
+
+		// Returns true if we're currently on the last slide
+		isLastSlide: function() {
+			if( currentSlide ) {
+				// Does this slide has next a sibling?
+				if( currentSlide.nextElementSibling ) return false;
+
+				// If it's vertical, does its parent have a next sibling?
+				if( isVerticalSlide( currentSlide ) && currentSlide.parentNode.nextElementSibling ) return false;
+
+				return true;
+			}
+
+			return false;
+		},
+
+		// Checks if reveal.js has been loaded and is ready for use
+		isReady: function() {
+			return loaded;
+		},
+
+		// Forward event binding to the reveal DOM element
+		addEventListener: function( type, listener, useCapture ) {
+			if( 'addEventListener' in window ) {
+				( dom.wrapper || document.querySelector( '.reveal' ) ).addEventListener( type, listener, useCapture );
+			}
+		},
+		removeEventListener: function( type, listener, useCapture ) {
+			if( 'addEventListener' in window ) {
+				( dom.wrapper || document.querySelector( '.reveal' ) ).removeEventListener( type, listener, useCapture );
+			}
+		},
+
+		// Programatically triggers a keyboard event
+		triggerKey: function( keyCode ) {
+			onDocumentKeyDown( { keyCode: keyCode } );
+		}
+	};
+
+	return Reveal;
+
+}));