text: /*!
   * reveal.js
   * http://lab.hakim.se/reveal-js
   * MIT licensed
   *
   * Copyright (C) 2013 Hakim El Hattab, http://hakim.se
   */
  var Reveal = (function(){
  
  	'use strict';
  
  	var SLIDES_SELECTOR = '.reveal .slides section',
  		HORIZONTAL_SLIDES_SELECTOR = '.reveal .slides>section',
  		VERTICAL_SLIDES_SELECTOR = '.reveal .slides>section.present>section',
  		HOME_SLIDE_SELECTOR = '.reveal .slides>section:first-child',
  
  		// Configurations 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: 1.0,
  
  			// Display controls in the bottom right corner
  			controls: true,
  
  			// Display a presentation progress bar
  			progress: true,
  
  			// Push each slide change to the browser history
  			history: false,
  
  			// Enable keyboard shortcuts for navigation
  			keyboard: true,
  
  			// Enable the slide overview mode
  			overview: true,
  
  			// Vertical centring 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,
  
  			// 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,
  
  			// Enable slide navigation via mouse wheel
  			mouseWheel: false,
  
  			// Apply a 3D roll to links on hover
  			rollingLinks: true,
  
  			// Opens links in an iframe preview overlay
  			previewLinks: false,
  
  			// Theme (see /css/theme)
  			theme: null,
  
  			// Transition style
  			transition: 'default', // default/cube/page/concave/zoom/linear/fade/none
  
  			// Transition speed
  			transitionSpeed: 'default', // default/fast/slow
  
  			// Transition style for full page slide backgrounds
  			backgroundTransition: 'default', // default/linear
  
  			// Script dependencies to load
  			dependencies: []
  		},
  
  		// The current auto-slide duration
  		autoSlide = 0,
  
  		// The horizontal and vertical index of the currently active slide
  		indexh = 0,
  		indexv = 0,
  
  		// The previous and current slide HTML elements
  		previousSlide,
  		currentSlide,
  
  		// 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,
  
  		// Cached references to DOM elements
  		dom = {},
  
  		// Detect support for CSS 3D transforms
  		supports3DTransforms =  '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,
  
  		// Detect support for CSS 2D transforms
  		supports2DTransforms =  '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,
  
  		// Throttles mouse wheel navigation
  		lastMouseWheelStep = 0,
  
  		// An interval used to automatically move on to the next slide
  		autoSlideTimeout = 0,
  
  		// Delays updates to the URL due to a Chrome thumbnailer bug
  		writeURLTimeout = 0,
  
  		// A delay used to activate the overview mode
  		activateOverviewTimeout = 0,
  
  		// A delay used to deactivate the overview mode
  		deactivateOverviewTimeout = 0,
  
  		// Flags if the interaction event listeners are bound
  		eventsAreBound = false,
  
  		// Holds information about the currently ongoing touch input
  		touch = {
  			startX: 0,
  			startY: 0,
  			startSpan: 0,
  			startCount: 0,
  			handled: false,
  			threshold: 80
  		};
  
  	/**
  	 * Starts up the presentation if the client is capable.
  	 */
  	function initialize( options ) {
  
  		if( !supports2DTransforms && !supports3DTransforms ) {
  			document.body.setAttribute( 'class', 'no-transforms' );
  
  			// If the browser doesn't support core features we won't be
  			// using JavaScript to control the presentation
  			return;
  		}
  
  		// Force a layout when the whole page, incl fonts, has loaded
  		window.addEventListener( 'load', layout, false );
  
  		// Copy options over to our config object
  		extend( config, options );
  
  		// Hide the address bar in mobile browsers
  		hideAddressBar();
  
  		// Loads the dependencies and continues to #start() once done
  		load();
  
  	}
  
  	/**
  	 * 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() {
  
  		// Cache references to key DOM elements
  		dom.theme = document.querySelector( '#theme' );
  		dom.wrapper = document.querySelector( '.reveal' );
  		dom.slides = document.querySelector( '.reveal .slides' );
  
  		// Background element
  		if( !document.querySelector( '.reveal .backgrounds' ) ) {
  			dom.background = document.createElement( 'div' );
  			dom.background.classList.add( 'backgrounds' );
  			dom.wrapper.appendChild( dom.background );
  		}
  
  		// Progress bar
  		if( !dom.wrapper.querySelector( '.progress' ) ) {
  			var progressElement = document.createElement( 'div' );
  			progressElement.classList.add( 'progress' );
  			progressElement.innerHTML = '<span></span>';
  			dom.wrapper.appendChild( progressElement );
  		}
  
  		// Arrow controls
  		if( !dom.wrapper.querySelector( '.controls' ) ) {
  			var controlsElement = document.createElement( 'aside' );
  			controlsElement.classList.add( 'controls' );
  			controlsElement.innerHTML = '<div class="navigate-left"></div>' +
  										'<div class="navigate-right"></div>' +
  										'<div class="navigate-up"></div>' +
  										'<div class="navigate-down"></div>';
  			dom.wrapper.appendChild( controlsElement );
  		}
  
  		// State background element [DEPRECATED]
  		if( !dom.wrapper.querySelector( '.state-background' ) ) {
  			var stateBackgroundElement = document.createElement( 'div' );
  			stateBackgroundElement.classList.add( 'state-background' );
  			dom.wrapper.appendChild( stateBackgroundElement );
  		}
  
  		// Overlay graphic which is displayed during the paused mode
  		if( !dom.wrapper.querySelector( '.pause-overlay' ) ) {
  			var pausedElement = document.createElement( 'div' );
  			pausedElement.classList.add( 'pause-overlay' );
  			dom.wrapper.appendChild( pausedElement );
  		}
  
  		// Cache references to elements
  		dom.progress = document.querySelector( '.reveal .progress' );
  		dom.progressbar = document.querySelector( '.reveal .progress span' );
  
  		if ( config.controls ) {
  			dom.controls = document.querySelector( '.reveal .controls' );
  
  			// 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' ) );
  		}
  
  	}
  
  	/**
  	 * 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() {
  
  		if( isPrintingPDF() ) {
  			document.body.classList.add( 'print-pdf' );
  		}
  
  		// Clear prior backgrounds
  		dom.background.innerHTML = '';
  		dom.background.classList.add( 'no-transition' );
  
  		// Helper method for creating a background element for the
  		// given slide
  		function _createBackground( slide, container ) {
  
  			var data = {
  				background: slide.getAttribute( 'data-background' ),
  				backgroundSize: slide.getAttribute( 'data-background-size' ),
  				backgroundImage: slide.getAttribute( 'data-background-image' ),
  				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' );
  			element.className = 'slide-background';
  
  			if( data.background ) {
  				// Auto-wrap image urls in url(...)
  				if( /^(http|file|\/\/)/gi.test( data.background ) || /\.(png|jpg|jpeg|gif|bmp)$/gi.test( data.background ) ) {
  					element.style.backgroundImage = 'url('+ data.background +')';
  				}
  				else {
  					element.style.background = data.background;
  				}
  			}
  
  			// Additional and optional background properties
  			if( data.backgroundSize ) element.style.backgroundSize = data.backgroundSize;
  			if( data.backgroundImage ) element.style.backgroundImage = 'url("' + data.backgroundImage + '")';
  			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 );
  
  			return element;
  
  		}
  
  		// Iterate over all horizontal slides
  		toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( slideh ) {
  
  			var backgroundStack;
  
  			if( isPrintingPDF() ) {
  				backgroundStack = _createBackground( slideh, slideh );
  			}
  			else {
  				backgroundStack = _createBackground( slideh, dom.background );
  			}
  
  			// Iterate over all vertical slides
  			toArray( slideh.querySelectorAll( 'section' ) ).forEach( function( slidev ) {
  
  				if( isPrintingPDF() ) {
  					_createBackground( slidev, slidev );
  				}
  				else {
  					_createBackground( slidev, backgroundStack );
  				}
  
  			} );
  
  		} );
  
  	}
  
  	/**
  	 * Hides the address bar if we're on a mobile device.
  	 */
  	function hideAddressBar() {
  
  		if( /iphone|ipod|android/gi.test( navigator.userAgent ) && !/crios/gi.test( navigator.userAgent ) ) {
  			// Events that should trigger the address bar to hide
  			window.addEventListener( 'load', removeAddressBar, false );
  			window.addEventListener( 'orientationchange', removeAddressBar, false );
  		}
  
  	}
  
  	/**
  	 * 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 = [];
  
  		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 );
  				}
  
  				// Extension may contain callback functions
  				if( typeof s.callback === 'function' ) {
  					head.ready( s.src.match( /([\w\d_\-]*)\.?js$|[^\\\/]*$/i )[0], s.callback );
  				}
  			}
  		}
  
  		// Called once synchronous scripts finish loading
  		function proceed() {
  			if( scriptsAsync.length ) {
  				// Load asynchronous scripts
  				head.js.apply( null, scriptsAsync );
  			}
  
  			start();
  		}
  
  		if( scripts.length ) {
  			head.ready( proceed );
  
  			// 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();
  
  		// Updates the presentation to match the current configuration values
  		configure();
  
  		// Read the initial hash
  		readURL();
  
  		// Notify listeners that the presentation is ready but use a 1ms
  		// timeout to ensure it's not fired synchronously after #initialize()
  		setTimeout( function() {
  			dispatchEvent( 'ready', {
  				'indexh': indexh,
  				'indexv': indexv,
  				'currentSlide': currentSlide
  			} );
  		}, 1 );
  
  	}
  
  	/**
  	 * Applies the configuration settings from the config
  	 * object. May be called multiple times.
  	 */
  	function configure( options ) {
  
  		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( supports3DTransforms === 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 );
  
  		if( dom.controls ) {
  			dom.controls.style.display = ( config.controls && dom.controls ) ? 'block' : 'none';
  		}
  
  		if( dom.progress ) {
  			dom.progress.style.display = ( config.progress && dom.progress ) ? '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' );
  		}
  
  		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]' );
  		}
  
  		// Load the theme in the config, if it's not already loaded
  		if( config.theme && dom.theme ) {
  			var themeURL = dom.theme.getAttribute( 'href' );
  			var themeFinder = /[^\/]*?(?=\.css)/;
  			var themeName = themeURL.match(themeFinder)[0];
  
  			if(  config.theme !== themeName ) {
  				themeURL = themeURL.replace(themeFinder, config.theme);
  				dom.theme.setAttribute( 'href', themeURL );
  			}
  		}
  
  		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.msPointerEnabled ) {
  				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 );
  		}
  
  		if ( config.progress && dom.progress ) {
  			dom.progress.addEventListener( 'click', onProgressClicked, false );
  		}
  
  		if ( config.controls && dom.controls ) {
  			[ 'touchstart', 'click' ].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 );
  		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 );
  
  		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 );
  		}
  
  		if ( config.controls && dom.controls ) {
  			[ '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 );
  
  	}
  
  	/**
  	 * 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 );
  
  	}
  
  	/**
  	 * 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( child.style.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;
  
  	}
  
  	/**
  	 * Checks if this instance is being used to print a PDF.
  	 */
  	function isPrintingPDF() {
  
  		return ( /print-pdf/gi ).test( window.location.search );
  
  	}
  
  	/**
  	 * Causes the address bar to hide on mobile devices,
  	 * more vertical space ftw.
  	 */
  	function removeAddressBar() {
  
  		if( window.orientation === 0 ) {
  			document.documentElement.style.overflow = 'scroll';
  			document.body.style.height = '120%';
  		}
  		else {
  			document.documentElement.style.overflow = '';
  			document.body.style.height = '100%';
  		}
  
  		setTimeout( function() {
  			window.scrollTo( 0, 1 );
  		}, 10 );
  
  	}
  
  	/**
  	 * Dispatches an event of the specified type from the
  	 * reveal DOM element.
  	 */
  	function dispatchEvent( type, properties ) {
  
  		var event = document.createEvent( "HTMLEvents", 1, 2 );
  		event.initEvent( type, true, true );
  		extend( event, properties );
  		dom.wrapper.dispatchEvent( event );
  
  	}
  
  	/**
  	 * Wrap all links in 3D goodness.
  	 */
  	function enableRollingLinks() {
  
  		if( supports3DTransforms && !( 'msPerspective' in document.body.style ) ) {
  			var anchors = document.querySelectorAll( SLIDES_SELECTOR + ' a:not(.image)' );
  
  			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 = document.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 openPreview( url ) {
  
  		closePreview();
  
  		dom.preview = document.createElement( 'div' );
  		dom.preview.classList.add( 'preview-link-overlay' );
  		dom.wrapper.appendChild( dom.preview );
  
  		dom.preview.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.preview.querySelector( 'iframe' ).addEventListener( 'load', function( event ) {
  			dom.preview.classList.add( 'loaded' );
  		}, false );
  
  		dom.preview.querySelector( '.close' ).addEventListener( 'click', function( event ) {
  			closePreview();
  			event.preventDefault();
  		}, false );
  
  		dom.preview.querySelector( '.external' ).addEventListener( 'click', function( event ) {
  			closePreview();
  		}, false );
  
  		setTimeout( function() {
  			dom.preview.classList.add( 'visible' );
  		}, 1 );
  
  	}
  
  	/**
  	 * Closes the iframe preview window.
  	 */
  	function closePreview() {
  
  		if( dom.preview ) {
  			dom.preview.setAttribute( 'src', '' );
  			dom.preview.parentNode.removeChild( dom.preview );
  			dom.preview = null;
  		}
  
  	}
  
  	/**
  	 * 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 ) {
  
  		var a = toArray( fragments );
  
  		a.forEach( function( el, idx ) {
  			if( !el.hasAttribute( 'data-fragment-index' ) ) {
  				el.setAttribute( 'data-fragment-index', idx );
  			}
  		} );
  
  		a.sort( function( l, r ) {
  			return l.getAttribute( 'data-fragment-index' ) - r.getAttribute( 'data-fragment-index');
  		} );
  
  		return a;
  
  	}
  
  	/**
  	 * Applies JavaScript-controlled layout rules to the
  	 * presentation.
  	 */
  	function layout() {
  
  		if( dom.wrapper && !isPrintingPDF() ) {
  
  			// Available space to scale within
  			var availableWidth = dom.wrapper.offsetWidth,
  				availableHeight = dom.wrapper.offsetHeight;
  
  			// Reduce available space by margin
  			availableWidth -= ( availableHeight * config.margin );
  			availableHeight -= ( availableHeight * config.margin );
  
  			// Dimensions of the content
  			var slideWidth = config.width,
  				slideHeight = config.height;
  
  			// Slide width may be a percentage of available width
  			if( typeof slideWidth === 'string' && /%$/.test( slideWidth ) ) {
  				slideWidth = parseInt( slideWidth, 10 ) / 100 * availableWidth;
  			}
  
  			// Slide height may be a percentage of available height
  			if( typeof slideHeight === 'string' && /%$/.test( slideHeight ) ) {
  				slideHeight = parseInt( slideHeight, 10 ) / 100 * availableHeight;
  			}
  
  			dom.slides.style.width = slideWidth + 'px';
  			dom.slides.style.height = slideHeight + 'px';
  
  			// Determine scale of content to fit within available space
  			scale = Math.min( availableWidth / slideWidth, availableHeight / slideHeight );
  
  			// Respect max/min scale settings
  			scale = Math.max( scale, config.minScale );
  			scale = Math.min( scale, config.maxScale );
  
  			// Prefer applying scale via zoom since Chrome blurs scaled content
  			// with nested transforms
  			if( typeof dom.slides.style.zoom !== 'undefined' && !navigator.userAgent.match( /(iphone|ipod|ipad|android)/gi ) ) {
  				dom.slides.style.zoom = scale;
  			}
  			// Apply scale transform as a fallback
  			else {
  				var transform = 'translate(-50%, -50%) scale('+ scale +') translate(50%, 50%)';
  
  				dom.slides.style.WebkitTransform = transform;
  				dom.slides.style.MozTransform = transform;
  				dom.slides.style.msTransform = transform;
  				dom.slides.style.OTransform = transform;
  				dom.slides.style.transform = transform;
  			}
  
  			// Select all slides, vertical and horizontal
  			var slides = toArray( document.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 ) {
  					// 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( - ( getAbsoluteHeight( slide ) / 2 ) - 20, -slideHeight / 2 ) + 'px';
  					}
  				}
  				else {
  					slide.style.top = '';
  				}
  
  			}
  
  			updateProgress();
  
  		}
  
  	}
  
  	/**
  	 * 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.
  	 *
  	 * Experimental feature, might be dropped if perf
  	 * can't be improved.
  	 */
  	function activateOverview() {
  
  		// Only proceed if enabled in config
  		if( config.overview ) {
  
  			// Don't auto-slide while in overview mode
  			cancelAutoSlide();
  
  			var wasActive = dom.wrapper.classList.contains( 'overview' );
  
  			dom.wrapper.classList.add( 'overview' );
  			dom.wrapper.classList.remove( 'exit-overview' );
  
  			clearTimeout( activateOverviewTimeout );
  			clearTimeout( deactivateOverviewTimeout );
  
  			// Not the pretties solution, but need to let the overview
  			// class apply first so that slides are measured accurately
  			// before we can position them
  			activateOverviewTimeout = setTimeout( function(){
  
  				var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );
  
  				for( var i = 0, len1 = horizontalSlides.length; i < len1; i++ ) {
  					var hslide = horizontalSlides[i],
  						hoffset = config.rtl ? -105 : 105,
  						htransform = 'translateZ(-2500px) translate(' + ( ( i - indexh ) * hoffset ) + '%, 0%)';
  
  					hslide.setAttribute( 'data-index-h', i );
  					hslide.style.display = 'block';
  					hslide.style.WebkitTransform = htransform;
  					hslide.style.MozTransform = htransform;
  					hslide.style.msTransform = htransform;
  					hslide.style.OTransform = htransform;
  					hslide.style.transform = htransform;
  
  					if( hslide.classList.contains( 'stack' ) ) {
  
  						var verticalSlides = hslide.querySelectorAll( 'section' );
  
  						for( var j = 0, len2 = verticalSlides.length; j < len2; j++ ) {
  							var verticalIndex = i === indexh ? indexv : getPreviousVerticalIndex( hslide );
  
  							var vslide = verticalSlides[j],
  								vtransform = 'translate(0%, ' + ( ( j - verticalIndex ) * 105 ) + '%)';
  
  							vslide.setAttribute( 'data-index-h', i );
  							vslide.setAttribute( 'data-index-v', j );
  							vslide.style.display = 'block';
  							vslide.style.WebkitTransform = vtransform;
  							vslide.style.MozTransform = vtransform;
  							vslide.style.msTransform = vtransform;
  							vslide.style.OTransform = vtransform;
  							vslide.style.transform = vtransform;
  
  							// Navigate to this slide on click
  							vslide.addEventListener( 'click', onOverviewSlideClicked, true );
  						}
  
  					}
  					else {
  
  						// Navigate to this slide on click
  						hslide.addEventListener( 'click', onOverviewSlideClicked, true );
  
  					}
  				}
  
  				layout();
  
  				if( !wasActive ) {
  					// Notify observers of the overview showing
  					dispatchEvent( 'overviewshown', {
  						'indexh': indexh,
  						'indexv': indexv,
  						'currentSlide': currentSlide
  					} );
  				}
  
  			}, 10 );
  
  		}
  
  	}
  
  	/**
  	 * Exits the slide overview and enters the currently
  	 * active slide.
  	 */
  	function deactivateOverview() {
  
  		// Only proceed if enabled in config
  		if( config.overview ) {
  
  			clearTimeout( activateOverviewTimeout );
  			clearTimeout( deactivateOverviewTimeout );
  
  			dom.wrapper.classList.remove( 'overview' );
  
  			// 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( 'exit-overview' );
  
  			deactivateOverviewTimeout = setTimeout( function () {
  				dom.wrapper.classList.remove( 'exit-overview' );
  			}, 10);
  
  			// Select all slides
  			var slides = toArray( document.querySelectorAll( SLIDES_SELECTOR ) );
  
  			for( var i = 0, len = slides.length; i < len; i++ ) {
  				var element = slides[i];
  
  				element.style.display = '';
  
  				// Resets all transforms to use the external styles
  				element.style.WebkitTransform = '';
  				element.style.MozTransform = '';
  				element.style.msTransform = '';
  				element.style.OTransform = '';
  				element.style.transform = '';
  
  				element.removeEventListener( 'click', onOverviewSlideClicked, true );
  			}
  
  			slide( indexh, indexv );
  
  			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 dom.wrapper.classList.contains( '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.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() {
  
  		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() {
  
  		if( isPaused() ) {
  			resume();
  		}
  		else {
  			pause();
  		}
  
  	}
  
  	/**
  	 * Checks if we are currently in the paused mode.
  	 */
  	function isPaused() {
  
  		return dom.wrapper.classList.contains( 'paused' );
  
  	}
  
  	/**
  	 * 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 = document.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 ) {
  			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,
  			indexvBefore = indexv;
  
  		// 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 );
  
  		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() );
  		}
  
  		// If the overview is active, re-activate it to update positions
  		if( isOverview() ) {
  			activateOverview();
  		}
  
  		// Update the URL hash after a delay since updating it mid-transition
  		// is likely to cause visual lag
  		writeURL( 1500 );
  
  		// 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' ) {
  			var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment' ) );
  
  			toArray( fragments ).forEach( function( fragment, indexf ) {
  				if( indexf < f ) {
  					fragment.classList.add( 'visible' );
  				}
  				else {
  					fragment.classList.remove( 'visible' );
  				}
  			} );
  		}
  
  		// 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' );
  
  			// Reset all slides upon navigate to home
  			// Issue: #285
  			if ( document.querySelector( HOME_SLIDE_SELECTOR ).classList.contains( 'present' ) ) {
  				// Launch async task
  				setTimeout( function () {
  					var slides = toArray( document.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 ) {
  			stopEmbeddedContent( previousSlide );
  			startEmbeddedContent( currentSlide );
  		}
  
  		updateControls();
  		updateProgress();
  		updateBackground();
  
  	}
  
  	/**
  	 * 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();
  
  		updateControls();
  		updateProgress();
  		updateBackground();
  
  	}
  
  	/**
  	 * 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( document.querySelectorAll( selector ) ),
  			slidesLength = slides.length;
  
  		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];
  
  				// Optimization; hide all slides that are three or more steps
  				// away from the present slide
  				if( isOverview() === false ) {
  					// The distance loops so that it measures 1 between the first
  					// and last slides
  					var distance = Math.abs( ( index - i ) % ( slidesLength - 3 ) ) || 0;
  
  					element.style.display = distance > 3 ? 'none' : 'block';
  				}
  
  				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', '' );
  
  				if( i < index ) {
  					// Any element previous to index is given the 'past' class
  					element.classList.add( reverse ? 'future' : 'past' );
  				}
  				else if( i > index ) {
  					// Any element subsequent to index is given the 'future' class
  					element.classList.add( reverse ? 'past' : 'future' );
  				}
  
  				// If this element contains vertical slides
  				if( element.querySelector( 'section' ) ) {
  					element.classList.add( 'stack' );
  				}
  			}
  
  			// Mark the current slide as present
  			slides[index].classList.add( 'present' );
  			slides[index].removeAttribute( '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( ' ' ) );
  			}
  
  			// If this slide has a data-autoslide attribtue associated use this as
  			// autoSlide value otherwise use the global configured time
  			var slideAutoSlide = slides[index].getAttribute( 'data-autoslide' );
  			if( slideAutoSlide ) {
  				autoSlide = parseInt( slideAutoSlide, 10 );
  			}
  			else {
  				autoSlide = config.autoSlide;
  			}
  
  		}
  		else {
  			// Since there are no slides we can't be anywhere beyond the
  			// zeroth index
  			index = 0;
  		}
  
  		return index;
  
  	}
  
  	/**
  	 * Updates the progress bar to reflect the current slide.
  	 */
  	function updateProgress() {
  
  		// Update progress if enabled
  		if( config.progress && dom.progress ) {
  
  			var horizontalSlides = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
  
  			// The number of past and total slides
  			var totalCount = document.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ).length;
  			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++;
  				}
  
  			}
  
  			dom.progressbar.style.width = ( pastCount / ( totalCount - 1 ) ) * window.innerWidth + 'px';
  
  		}
  
  	}
  
  	/**
  	 * Updates the state of all control/navigation arrows.
  	 */
  	function updateControls() {
  
  		if ( config.controls && dom.controls ) {
  
  			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.
  	 */
  	function updateBackground() {
  
  		// Update the classes of all backgrounds to match the 
  		// states of their slides (past/present/future)
  		toArray( dom.background.childNodes ).forEach( function( backgroundh, h ) {
  
  			// Reverse past/future classes when in RTL mode
  			var horizontalPast = config.rtl ? 'future' : 'past',
  				horizontalFuture = config.rtl ? 'past' : 'future';
  
  			backgroundh.className = 'slide-background ' + ( h < indexh ? horizontalPast : h > indexh ? horizontalFuture : 'present' );
  
  			toArray( backgroundh.childNodes ).forEach( function( backgroundv, v ) {
  
  				backgroundv.className = 'slide-background ' + ( v < indexv ? 'past' : v > indexv ? 'future' : 'present' );
  
  			} );
  
  		} );
  
  		// Allow the first background to apply without transition
  		setTimeout( function() {
  			dom.background.classList.remove( 'no-transition' );
  		}, 1 );
  
  	}
  
  	/**
  	 * Determine what available routes there are for navigation.
  	 *
  	 * @return {Object} containing four booleans: left/right/up/down
  	 */
  	function availableRoutes() {
  
  		var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
  			verticalSlides = document.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 };
  		}
  
  	}
  
  	/**
  	 * Start playback of any embedded content inside of
  	 * the targeted slide.
  	 */
  	function startEmbeddedContent( slide ) {
  
  		if( slide ) {
  			// HTML5 media elements
  			toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
  				if( el.hasAttribute( 'data-autoplay' ) ) {
  					el.play();
  				}
  			} );
  
  			// YouTube embeds
  			toArray( slide.querySelectorAll( 'iframe[src*="youtube.com/embed/"]' ) ).forEach( function( el ) {
  				if( el.hasAttribute( 'data-autoplay' ) ) {
  					el.contentWindow.postMessage('{"event":"command","func":"playVideo","args":""}', '*');
  				}
  			});
  		}
  
  	}
  
  	/**
  	 * Stop playback of any embedded content inside of
  	 * the targeted slide.
  	 */
  	function stopEmbeddedContent( slide ) {
  
  		if( slide ) {
  			// HTML5 media elements
  			toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
  				if( !el.hasAttribute( 'data-ignore' ) ) {
  					el.pause();
  				}
  			} );
  
  			// YouTube embeds
  			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":""}', '*');
  				}
  			});
  		}
  
  	}
  
  	/**
  	 * 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 ) {
  			// Find the slide with the specified name
  			var element = document.querySelector( '#' + 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, indexv );
  			}
  		}
  		else {
  			// Read the index components of the hash
  			var h = parseInt( bits[0], 10 ) || 0,
  				v = parseInt( bits[1], 10 ) || 0;
  
  			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 {
  				var url = '/';
  
  				// If the current slide has an ID, use that as a named link
  				if( currentSlide && typeof currentSlide.getAttribute( 'id' ) === 'string' ) {
  					url = '/' + currentSlide.getAttribute( '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( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
  
  			// Now that we know which the horizontal slide is, get its index
  			h = Math.max( horizontalSlides.indexOf( slideh ), 0 );
  
  			// 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 visibleFragments = currentSlide.querySelectorAll( '.fragment.visible' );
  			if( visibleFragments.length ) {
  				f = visibleFragments.length;
  			}
  		}
  
  		return { h: h, v: v, f: f };
  
  	}
  
  	/**
  	 * Navigate to the next slide fragment.
  	 *
  	 * @return {Boolean} true if there was a next fragment,
  	 * false otherwise
  	 */
  	function nextFragment() {
  
  		if( currentSlide && config.fragments ) {
  			var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment:not(.visible)' ) );
  
  			if( fragments.length ) {
  				// Find the index of the next fragment
  				var index = fragments[0].getAttribute( 'data-fragment-index' );
  
  				// Find all fragments with the same index
  				fragments = currentSlide.querySelectorAll( '.fragment[data-fragment-index="'+ index +'"]' );
  
  				toArray( fragments ).forEach( function( element ) {
  					element.classList.add( 'visible' );
  				} );
  
  				// Notify subscribers of the change
  				dispatchEvent( 'fragmentshown', { fragment: fragments[0], fragments: fragments } );
  
  				updateControls();
  				return true;
  			}
  		}
  
  		return false;
  
  	}
  
  	/**
  	 * Navigate to the previous slide fragment.
  	 *
  	 * @return {Boolean} true if there was a previous fragment,
  	 * false otherwise
  	 */
  	function previousFragment() {
  
  		if( currentSlide && config.fragments ) {
  			var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment.visible' ) );
  
  			if( fragments.length ) {
  				// Find the index of the previous fragment
  				var index = fragments[ fragments.length - 1 ].getAttribute( 'data-fragment-index' );
  
  				// Find all fragments with the same index
  				fragments = currentSlide.querySelectorAll( '.fragment[data-fragment-index="'+ index +'"]' );
  
  				toArray( fragments ).forEach( function( f ) {
  					f.classList.remove( 'visible' );
  				} );
  
  				// Notify subscribers of the change
  				dispatchEvent( 'fragmenthidden', { fragment: fragments[0], fragments: fragments } );
  
  				updateControls();
  				return true;
  			}
  		}
  
  		return false;
  
  	}
  
  	/**
  	 * Cues a new automated slide if enabled in the config.
  	 */
  	function cueAutoSlide() {
  
  		clearTimeout( autoSlideTimeout );
  
  		// Cue the next auto-slide if enabled
  		if( autoSlide && !isPaused() && !isOverview() ) {
  			autoSlideTimeout = setTimeout( navigateNext, autoSlide );
  		}
  
  	}
  
  	/**
  	 * Cancels any ongoing request to auto-slide.
  	 */
  	function cancelAutoSlide() {
  
  		clearTimeout( autoSlideTimeout );
  
  	}
  
  	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 = document.querySelector( HORIZONTAL_SLIDES_SELECTOR + '.past:nth-child(' + indexh + ')' );
  
  				if( previousSlide ) {
  					var v = ( previousSlide.querySelectorAll( 'section' ).length - 1 ) || undefined;
  					var h = indexh - 1;
  					slide( h, v );
  				}
  			}
  		}
  
  	}
  
  	/**
  	 * Same as #navigatePrev() but navigates forwards.
  	 */
  	function navigateNext() {
  
  		// Prioritize revealing fragments
  		if( nextFragment() === false ) {
  			availableRoutes().down ? navigateDown() : navigateRight();
  		}
  
  		// If auto-sliding is enabled we need to cue up
  		// another timeout
  		cueAutoSlide();
  
  	}
  
  
  	// --------------------------------------------------------------------//
  	// ----------------------------- EVENTS -------------------------------//
  	// --------------------------------------------------------------------//
  
  
  	/**
  	 * Handler for the document level 'keydown' event.
  	 *
  	 * @param {Object} event
  	 */
  	function onDocumentKeyDown( event ) {
  
  		// Check if there's a focused element that could be using
  		// the keyboard
  		var activeElement = document.activeElement;
  		var hasFocus = !!( document.activeElement && ( document.activeElement.type || document.activeElement.href || document.activeElement.contentEditable !== 'inherit' ) );
  
  		// Disregard the event if there's a focused element or a
  		// keyboard modifier key is present
  		if( hasFocus || (event.shiftKey && event.keyCode !== 32) || event.altKey || event.ctrlKey || event.metaKey ) return;
  
  		// While paused only allow "unpausing" keyboard events (b and .)
  		if( isPaused() && [66,190,191].indexOf( event.keyCode ) === -1 ) {
  			return false;
  		}
  
  		var triggered = false;
  
  		// 1. User defined key bindings
  		if( typeof config.keyboard === 'object' ) {
  
  			for( var key in config.keyboard ) {
  
  				// Check if this binding matches the pressed key
  				if( parseInt( key, 10 ) === event.keyCode ) {
  
  					var value = config.keyboard[ key ];
  
  					// Calback 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;
  				// b, period, Logitech presenter tools "black screen" button
  				case 66: case 190: case 191: togglePause(); break;
  				// f
  				case 70: enterFullscreen(); break;
  				default:
  					triggered = false;
  			}
  
  		}
  
  		// If the input resulted in a triggered action we should prevent
  		// the browsers default behavior
  		if( triggered ) {
  			event.preventDefault();
  		}
  		else if ( event.keyCode === 27 && supports3DTransforms ) {
  			toggleOverview();
  
  			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 ) {
  
  		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 ) {
  
  		// Each touch should only trigger one action
  		if( !touch.handled ) {
  			var currentX = event.touches[0].clientX;
  			var currentY = event.touches[0].clientY;
  
  			// If the touch started off 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.handled = 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.handled = true;
  					navigateLeft();
  				}
  				else if( deltaX < -touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
  					touch.handled = true;
  					navigateRight();
  				}
  				else if( deltaY > touch.threshold ) {
  					touch.handled = true;
  					navigateUp();
  				}
  				else if( deltaY < -touch.threshold ) {
  					touch.handled = true;
  					navigateDown();
  				}
  
  				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.handled = false;
  
  	}
  
  	/**
  	 * Convert pointer down to touch start.
  	 */
  	function onPointerDown( event ) {
  
  		if( event.pointerType === event.MSPOINTER_TYPE_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.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.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 ) {
  
  		event.preventDefault();
  
  		var slidesTotal = toArray( document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).length;
  		var slideIndex = Math.floor( ( event.clientX / dom.wrapper.offsetWidth ) * slidesTotal );
  
  		slide( slideIndex );
  
  	}
  
  	/**
  	 * Event handler for navigation control buttons.
  	 */
  	function onNavigateLeftClicked( event ) { event.preventDefault(); navigateLeft(); }
  	function onNavigateRightClicked( event ) { event.preventDefault(); navigateRight(); }
  	function onNavigateUpClicked( event ) { event.preventDefault(); navigateUp(); }
  	function onNavigateDownClicked( event ) { event.preventDefault(); navigateDown(); }
  	function onNavigatePrevClicked( event ) { event.preventDefault(); navigatePrev(); }
  	function onNavigateNextClicked( event ) { event.preventDefault(); navigateNext(); }
  
  	/**
  	 * Handler for the window level 'hashchange' event.
  	 */
  	function onWindowHashChange( event ) {
  
  		readURL();
  
  	}
  
  	/**
  	 * Handler for the window level 'resize' event.
  	 */
  	function onWindowResize( event ) {
  
  		layout();
  
  	}
  
  	/**
  	 * 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 ) {
  
  		var url = event.target.getAttribute( 'href' );
  		if( url ) {
  			openPreview( url );
  			event.preventDefault();
  		}
  
  	}
  
  
  	// --------------------------------------------------------------------//
  	// ------------------------------- API --------------------------------//
  	// --------------------------------------------------------------------//
  
  
  	return {
  		initialize: initialize,
  		configure: configure,
  		sync: sync,
  
  		// Navigation methods
  		slide: slide,
  		left: navigateLeft,
  		right: navigateRight,
  		up: navigateUp,
  		down: navigateDown,
  		prev: navigatePrev,
  		next: navigateNext,
  		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,
  
  		// State checks
  		isOverview: isOverview,
  		isPaused: isPaused,
  
  		// Adds or removes all internal event listeners (such as keyboard)
  		addEventListeners: addEventListeners,
  		removeEventListeners: removeEventListeners,
  
  		// Returns the indices of the current, or specified, slide
  		getIndices: getIndices,
  
  		// Returns the slide at the specified index, y is optional
  		getSlide: function( x, y ) {
  			var horizontalSlide = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR )[ x ];
  			var verticalSlides = horizontalSlide && horizontalSlide.querySelectorAll( 'section' );
  
  			if( typeof y !== 'undefined' ) {
  				return verticalSlides ? verticalSlides[ y ] : undefined;
  			}
  
  			return horizontalSlide;
  		},
  
  		// 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();
  			} );
  
  			return query;
  		},
  
  		// Returns true if we're currently on the first slide
  		isFirstSlide: function() {
  			return document.querySelector( SLIDES_SELECTOR + '.past' ) == null ? true : false;
  		},
  
  		// Returns true if we're currently on the last slide
  		isLastSlide: function() {
  			if( currentSlide && currentSlide.classList.contains( '.stack' ) ) {
  				return currentSlide.querySelector( SLIDES_SELECTOR + '.future' ) == null ? true : false;
  			}
  			else {
  				return document.querySelector( SLIDES_SELECTOR + '.future' ) == null ? true : false;
  			}
  		},
  
  		// 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 );
  			}
  		}
  	};
  
  })();
  