/*!
 * Copyright 2016 Google Inc. All Rights Reserved.
 * Licensed under the W3C SOFTWARE AND DOCUMENT NOTICE AND LICENSE.
 *  https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document
 */
!function(){'use strict';if('object'==typeof window)if('IntersectionObserver'in window&&'IntersectionObserverEntry'in window&&'intersectionRatio'in window.IntersectionObserverEntry.prototype)'isIntersecting'in window.IntersectionObserverEntry.prototype||Object.defineProperty(window.IntersectionObserverEntry.prototype,'isIntersecting',{get:function(){return this.intersectionRatio>0}});else{var t=function(t){for(var e=window.document,n=i(e);n;)n=i(e=n.ownerDocument);return e}(),e=[],n=null,o=null;s.prototype.THROTTLE_TIMEOUT=100,s.prototype.POLL_INTERVAL=null,s.prototype.USE_MUTATION_OBSERVER=!0,s._setupCrossOriginUpdater=function(){return n||(n=function(t,n){o=t&&n?l(t,n):{top:0,bottom:0,left:0,right:0,width:0,height:0},e.forEach(function(t){t._checkForIntersections()})}),n},s._resetCrossOriginUpdater=function(){n=null,o=null},s.prototype.observe=function(t){if(!this._observationTargets.some(function(e){return e.element==t})){if(!t||1!=t.nodeType)throw new Error('target must be an Element');this._registerInstance(),this._observationTargets.push({element:t,entry:null}),this._monitorIntersections(t.ownerDocument),this._checkForIntersections()}},s.prototype.unobserve=function(t){this._observationTargets=this._observationTargets.filter(function(e){return e.element!=t}),this._unmonitorIntersections(t.ownerDocument),0==this._observationTargets.length&&this._unregisterInstance()},s.prototype.disconnect=function(){this._observationTargets=[],this._unmonitorAllIntersections(),this._unregisterInstance()},s.prototype.takeRecords=function(){var t=this._queuedEntries.slice();return this._queuedEntries=[],t},s.prototype._initThresholds=function(t){var e=t||[0];return Array.isArray(e)||(e=[e]),e.sort().filter(function(t,e,n){if('number'!=typeof t||isNaN(t)||t<0||t>1)throw new Error('threshold must be a number between 0 and 1 inclusively');return t!==n[e-1]})},s.prototype._parseRootMargin=function(t){var e=(t||'0px').split(/\s+/).map(function(t){var e=/^(-?\d*\.?\d+)(px|%)$/.exec(t);if(!e)throw new Error('rootMargin must be specified in pixels or percent');return{value:parseFloat(e[1]),unit:e[2]}});return e[1]=e[1]||e[0],e[2]=e[2]||e[0],e[3]=e[3]||e[1],e},s.prototype._monitorIntersections=function(e){var n=e.defaultView;if(n&&-1==this._monitoringDocuments.indexOf(e)){var o=this._checkForIntersections,r=null,s=null;if(this.POLL_INTERVAL?r=n.setInterval(o,this.POLL_INTERVAL):(h(n,'resize',o,!0),h(e,'scroll',o,!0),this.USE_MUTATION_OBSERVER&&'MutationObserver'in n&&(s=new n.MutationObserver(o)).observe(e,{attributes:!0,childList:!0,characterData:!0,subtree:!0})),this._monitoringDocuments.push(e),this._monitoringUnsubscribes.push(function(){var t=e.defaultView;t&&(r&&t.clearInterval(r),c(t,'resize',o,!0)),c(e,'scroll',o,!0),s&&s.disconnect()}),e!=(this.root&&this.root.ownerDocument||t)){var u=i(e);u&&this._monitorIntersections(u.ownerDocument)}}},s.prototype._unmonitorIntersections=function(e){var n=this._monitoringDocuments.indexOf(e);if(-1!=n){var o=this.root&&this.root.ownerDocument||t;if(!this._observationTargets.some(function(t){var n=t.element.ownerDocument;if(n==e)return!0;for(;n&&n!=o;){var r=i(n);if((n=r&&r.ownerDocument)==e)return!0}return!1})){var r=this._monitoringUnsubscribes[n];if(this._monitoringDocuments.splice(n,1),this._monitoringUnsubscribes.splice(n,1),r(),e!=o){var s=i(e);s&&this._unmonitorIntersections(s.ownerDocument)}}}},s.prototype._unmonitorAllIntersections=function(){var t=this._monitoringUnsubscribes.slice(0);this._monitoringDocuments.length=0,this._monitoringUnsubscribes.length=0;for(var e=0;e<t.length;e++)t[e]()},s.prototype._checkForIntersections=function(){if(this.root||!n||o){var t=this._rootIsInDom(),e=t?this._getRootRect():{top:0,bottom:0,left:0,right:0,width:0,height:0};this._observationTargets.forEach(function(o){var i=o.element,s=u(i),h=this._rootContainsTarget(i),c=o.entry,a=t&&h&&this._computeTargetAndRootIntersection(i,s,e),l=o.entry=new r({time:window.performance&&performance.now&&performance.now(),target:i,boundingClientRect:s,rootBounds:n&&!this.root?null:e,intersectionRect:a});c?t&&h?this._hasCrossedThreshold(c,l)&&this._queuedEntries.push(l):c&&c.isIntersecting&&this._queuedEntries.push(l):this._queuedEntries.push(l)},this),this._queuedEntries.length&&this._callback(this.takeRecords(),this)}},s.prototype._computeTargetAndRootIntersection=function(e,i,r){if('none'!=window.getComputedStyle(e).display){for(var s,h,c,a,f,d,g,m,v=i,_=p(e),b=!1;!b&&_;){var w=null,y=1==_.nodeType?window.getComputedStyle(_):{};if('none'==y.display)return null;if(_==this.root||9==_.nodeType)if(b=!0,_==this.root||_==t)n&&!this.root?!o||0==o.width&&0==o.height?(_=null,w=null,v=null):w=o:w=r;else{var I=p(_),E=I&&u(I),T=I&&this._computeTargetAndRootIntersection(I,E,r);E&&T?(_=I,w=l(E,T)):(_=null,v=null)}else{var R=_.ownerDocument;_!=R.body&&_!=R.documentElement&&'visible'!=y.overflow&&(w=u(_))}if(w&&(s=w,h=v,c=void 0,a=void 0,f=void 0,d=void 0,g=void 0,m=void 0,c=Math.max(s.top,h.top),a=Math.min(s.bottom,h.bottom),f=Math.max(s.left,h.left),d=Math.min(s.right,h.right),m=a-c,v=(g=d-f)>=0&&m>=0&&{top:c,bottom:a,left:f,right:d,width:g,height:m}||null),!v)break;_=_&&p(_)}return v}},s.prototype._getRootRect=function(){var e;if(this.root)e=u(this.root);else{var n=t.documentElement,o=t.body;e={top:0,left:0,right:n.clientWidth||o.clientWidth,width:n.clientWidth||o.clientWidth,bottom:n.clientHeight||o.clientHeight,height:n.clientHeight||o.clientHeight}}return this._expandRectByRootMargin(e)},s.prototype._expandRectByRootMargin=function(t){var e=this._rootMarginValues.map(function(e,n){return'px'==e.unit?e.value:e.value*(n%2?t.width:t.height)/100}),n={top:t.top-e[0],right:t.right+e[1],bottom:t.bottom+e[2],left:t.left-e[3]};return n.width=n.right-n.left,n.height=n.bottom-n.top,n},s.prototype._hasCrossedThreshold=function(t,e){var n=t&&t.isIntersecting?t.intersectionRatio||0:-1,o=e.isIntersecting?e.intersectionRatio||0:-1;if(n!==o)for(var i=0;i<this.thresholds.length;i++){var r=this.thresholds[i];if(r==n||r==o||r<n!=r<o)return!0}},s.prototype._rootIsInDom=function(){return!this.root||f(t,this.root)},s.prototype._rootContainsTarget=function(e){return f(this.root||t,e)&&(!this.root||this.root.ownerDocument==e.ownerDocument)},s.prototype._registerInstance=function(){e.indexOf(this)<0&&e.push(this)},s.prototype._unregisterInstance=function(){var t=e.indexOf(this);-1!=t&&e.splice(t,1)},window.IntersectionObserver=s,window.IntersectionObserverEntry=r}function i(t){try{return t.defaultView&&t.defaultView.frameElement||null}catch(t){return null}}function r(t){this.time=t.time,this.target=t.target,this.rootBounds=a(t.rootBounds),this.boundingClientRect=a(t.boundingClientRect),this.intersectionRect=a(t.intersectionRect||{top:0,bottom:0,left:0,right:0,width:0,height:0}),this.isIntersecting=!!t.intersectionRect;var e=this.boundingClientRect,n=e.width*e.height,o=this.intersectionRect,i=o.width*o.height;this.intersectionRatio=n?Number((i/n).toFixed(4)):this.isIntersecting?1:0}function s(t,e){var n,o,i,r=e||{};if('function'!=typeof t)throw new Error('callback must be a function');if(r.root&&1!=r.root.nodeType)throw new Error('root must be an Element');this._checkForIntersections=(n=this._checkForIntersections.bind(this),o=this.THROTTLE_TIMEOUT,i=null,function(){i||(i=setTimeout(function(){n(),i=null},o))}),this._callback=t,this._observationTargets=[],this._queuedEntries=[],this._rootMarginValues=this._parseRootMargin(r.rootMargin),this.thresholds=this._initThresholds(r.threshold),this.root=r.root||null,this.rootMargin=this._rootMarginValues.map(function(t){return t.value+t.unit}).join(' '),this._monitoringDocuments=[],this._monitoringUnsubscribes=[]}function h(t,e,n,o){'function'==typeof t.addEventListener?t.addEventListener(e,n,o||!1):'function'==typeof t.attachEvent&&t.attachEvent('on'+e,n)}function c(t,e,n,o){'function'==typeof t.removeEventListener?t.removeEventListener(e,n,o||!1):'function'==typeof t.detatchEvent&&t.detatchEvent('on'+e,n)}function u(t){var e;try{e=t.getBoundingClientRect()}catch(t){}return e?(e.width&&e.height||(e={top:e.top,right:e.right,bottom:e.bottom,left:e.left,width:e.right-e.left,height:e.bottom-e.top}),e):{top:0,bottom:0,left:0,right:0,width:0,height:0}}function a(t){return!t||'x'in t?t:{top:t.top,y:t.top,bottom:t.bottom,left:t.left,x:t.left,right:t.right,width:t.width,height:t.height}}function l(t,e){var n=e.top-t.top,o=e.left-t.left;return{top:n,left:o,height:e.height,width:e.width,bottom:n+e.height,right:o+e.width}}function f(t,e){for(var n=e;n;){if(n==t)return!0;n=p(n)}return!1}function p(e){var n=e.parentNode;return 9==e.nodeType&&e!=t?i(e):n&&11==n.nodeType&&n.host?n.host:n&&n.assignedSlot?n.assignedSlot.parentNode:n}}();