<section class="cd-section">
		<p>
			Lorem ipsum dolor sit amet, consectetur adipisicing elit. Non ipsum repudiandae sequi ut optio reiciendis consectetur, cum, a provident, iusto quod esse, perferendis iure iste! Quidem itaque, exercitationem aliquam, mollitia recusandae repellat dolores quibusdam minima quae reprehenderit ut, reiciendis officia.
		</p>

		<div class="cd-modal-action">
			<a href="#0" class="btn" data-type="modal-trigger">Fire Modal Window</a>
			<span class="cd-modal-bg"></span>
		</div> <!-- cd-modal-action -->

		<div class="cd-modal">
			<div class="cd-modal-content">
				<p>
					Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad modi repellendus, optio eveniet eligendi molestiae? Fugiat, temporibus! A rerum pariatur neque laborum earum, illum voluptatibus eum voluptatem fugiat, porro animi tempora? Sit harum nulla, nesciunt molestias, iusto aliquam aperiam est qui possimus reprehenderit ipsam ea aut assumenda inventore iste! Animi quaerat facere repudiandae earum quisquam accusamus tempora, delectus nesciunt, provident quae aliquam, voluptatum beatae quis similique in maiores repellat eligendi voluptas veniam optio illum vero! Eius, dignissimos esse eligendi veniam.
				</p>

				<p>
					Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad modi repellendus, optio eveniet eligendi molestiae? Fugiat, temporibus! A rerum pariatur neque laborum earum, illum voluptatibus eum voluptatem fugiat, porro animi tempora? Sit harum nulla, nesciunt molestias, iusto aliquam aperiam est qui possimus reprehenderit ipsam ea aut assumenda inventore iste! Animi quaerat facere repudiandae earum quisquam accusamus tempora, delectus nesciunt, provident quae aliquam, voluptatum beatae quis similique in maiores repellat eligendi voluptas veniam optio illum vero! Eius, dignissimos esse eligendi veniam.
				</p>

				<p>
					Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad modi repellendus, optio eveniet eligendi molestiae? Fugiat, temporibus! A rerum pariatur neque laborum earum, illum voluptatibus eum voluptatem fugiat, porro animi tempora? Sit harum nulla, nesciunt molestias, iusto aliquam aperiam est qui possimus reprehenderit ipsam ea aut assumenda inventore iste! Animi quaerat facere repudiandae earum quisquam accusamus tempora, delectus nesciunt, provident quae aliquam, voluptatum beatae quis similique in maiores repellat eligendi voluptas veniam optio illum vero! Eius, dignissimos esse eligendi veniam.
				</p>
			</div> <!-- cd-modal-content -->
		</div> <!-- cd-modal -->

		<a href="#0" class="cd-modal-close">Close</a>
	</section> <!-- .cd-section -->

@import "bourbon";

// breakpoints
   
$S:     480px;   
$M:     768px;     
$L:     1170px;     

// media queries

@mixin MQ($canvas) {
  @if $canvas == S {
   @media only screen and (min-width: $S) { @content; } 
  }
  @else if $canvas == M {
   @media only screen and (min-width: $M) { @content; } 
  }
  @else if $canvas == L {
   @media only screen and (min-width: $L) { @content; } 
  }
}

// antialiasing mode font rendering

@mixin font-smoothing {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

// colors

$color-1: #34383c; // Outer Space
$color-2: #03bb91; // Caribbean Green
$color-3: #ffffff; // White

// fonts 

$primary-font: 'Source Sans Pro', sans-serif;

/* -------------------------------- 

Primary style

-------------------------------- */

*, *::after, *::before {
	@include box-sizing(border-box);
}

html {
	font-size: 62.5%;
}

body {
	font: {
		size: 1.6rem;
		family: $primary-font;
	}
	color: $color-1;
	background-color: $color-3;

	&.overflow-hidden {
		/* used when modal is visible */
		overflow: hidden;
	}
}

a {
	color: $color-2;
	text-decoration: none;
}

/* -------------------------------- 

Main Components 

-------------------------------- */

.cd-section {
	padding: 2em 5%;
	text-align: center;
	background-color: $color-2;

	p {
		margin: 2em 0;
		line-height: 1.6;
		color: $color-3;
		@include font-smoothing;
	}

	@include MQ(M) {
		padding: 4em 10%;

		p {
			font-size: 1.8rem;
			line-height: 2;
		}
	}

	@include MQ(L) {
		padding: 4em 20%;
	}
}

.cd-modal {
	position: fixed;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;

	visibility: hidden;
	opacity: 0;
	pointer-events: none;

	@include transition(visibility 0s .3s, opacity .3s 0s, z-index 0s .3s);

	&::after {
		/* gradient overlay at bottom of modal window */
		content: '';
		position: absolute;
		left: 0;
		bottom: 0;
		width: 100%;
		height: 60px;
		pointer-events: none;
		background: transparent;
		@include background(linear-gradient(to top,rgba($color-1, 1), rgba($color-1, 0)));
	}

	.cd-modal-content {
		height: 100%;
		width: 100%;
		padding: 3em 5%;
		text-align: left;
		overflow-y: auto; 
		@include font-smoothing; 
	}

	p {
		color: $color-3;
		line-height: 1.6;
		margin: 2em 0;
	}

	.modal-is-visible & {
		z-index: 1;
		visibility: visible;
		opacity: 1;
		pointer-events: auto;
		
		@include transition(visibility 0s 0s, opacity .3s 0s, z-index 0s 0s);

		.cd-modal-content {
			-webkit-overflow-scrolling: touch;
		}
	}

	@include MQ(M) {

		.cd-modal-content { 
			padding: 4em 10%;
		}
	}

	@include MQ(L) {

		.cd-modal-content { 
			padding: 6em 20%;
		}

		p {
			font-size: 2rem;
			line-height: 2;
		}
	}
}

.cd-modal-action {
	position: relative;

	.btn, .cd-modal-bg {
		display: inline-block;
		height: 4em;
		background-color: $color-1;
	}
	
	.btn {
		width: 12.5em;
		border-radius: 5em;

		color: $color-3;
		line-height: 4em;
		white-space: nowrap;
		font-weight: 700;
		@include font-smoothing;
		
		@include transition(color .2s .3s, width .3s 0s);

		&.to-circle {
			width: 4em;
			color: transparent;
			@include transition(color .2s 0s, width .3s .2s);
		}
	}

	.cd-modal-bg {
		position: absolute;
		z-index: 1;
		left: 50%;
    	top: 0;
		width: 4em;
		border-radius: 50%;
		opacity: 0;
		visibility: hidden;
    	@include transform(translateZ(0));
    	@include transform(translateX(-2em));
		@include transition(visibility 0s .5s);

		&.is-visible {
			opacity: 1;
			visibility: visible;
		}
	}
}

.cd-modal-close {
	position: fixed;
	z-index: 1;
	top: 20px;
	right: 5%;

	height: 50px;
	width: 50px;
	border-radius: 50%;
	
	background: rgba(#000, .3) url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/148866/cd-icon-close_copy.svg) no-repeat center center;
	
	/* image replacement */
	overflow: hidden;
	text-indent: 100%;
	white-space: nowrap;

	visibility: hidden;
	opacity: 0;
	@include transform(translateZ(0));
	@include transform(scale(0));
	@include transition(transform .3s 0s, visibility 0s .3s, opacity .3s 0s);

	.no-touch &:hover {
		background-color: rgba(#000, .5);
	}

	.modal-is-visible & {
		visibility: visible;
		opacity: 1;
		@include transition(transform .3s 0s, visibility 0s 0s, opacity .3s 0s);
		@include transform(scale(1));
	}

	@include MQ(M) {
		top: 70px;
	}
}

jQuery(document).ready(function($){
	//trigger the animation - open modal window
	$('[data-type="modal-trigger"]').on('click', function(){
		var actionBtn = $(this),
			scaleValue = retrieveScale(actionBtn.next('.cd-modal-bg'));
		
		actionBtn.addClass('to-circle');
		actionBtn.next('.cd-modal-bg').addClass('is-visible').one('webkitTransitionEnd otransitionend oTransitionEnd msTransitionEnd transitionend', function(){
			animateLayer(actionBtn.next('.cd-modal-bg'), scaleValue, true);
		});

		//if browser doesn't support transitions...
		if(actionBtn.parents('.no-csstransitions').length > 0 ) animateLayer(actionBtn.next('.cd-modal-bg'), scaleValue, true);
	});

	//trigger the animation - close modal window
	$('.cd-section .cd-modal-close').on('click', function(){
		closeModal();
	});
	$(document).keyup(function(event){
		if(event.which=='27') closeModal();
	});

	$(window).on('resize', function(){
		//on window resize - update cover layer dimention and position
		if($('.cd-section.modal-is-visible').length > 0) window.requestAnimationFrame(updateLayer);
	});

	function retrieveScale(btn) {
		var btnRadius = btn.width()/2,
			left = btn.offset().left + btnRadius,
			top = btn.offset().top + btnRadius - $(window).scrollTop(),
			scale = scaleValue(top, left, btnRadius, $(window).height(), $(window).width());

		btn.css('position', 'fixed').velocity({
			top: top - btnRadius,
			left: left - btnRadius,
			translateX: 0,
		}, 0);

		return scale;
	}

	function scaleValue( topValue, leftValue, radiusValue, windowW, windowH) {
		var maxDistHor = ( leftValue > windowW/2) ? leftValue : (windowW - leftValue),
			maxDistVert = ( topValue > windowH/2) ? topValue : (windowH - topValue);
		return Math.ceil(Math.sqrt( Math.pow(maxDistHor, 2) + Math.pow(maxDistVert, 2) )/radiusValue);
	}

	function animateLayer(layer, scaleVal, bool) {
		layer.velocity({ scale: scaleVal }, 400, function(){
			$('body').toggleClass('overflow-hidden', bool);
			(bool) 
				? layer.parents('.cd-section').addClass('modal-is-visible').end().off('webkitTransitionEnd otransitionend oTransitionEnd msTransitionEnd transitionend')
				: layer.removeClass('is-visible').removeAttr( 'style' ).siblings('[data-type="modal-trigger"]').removeClass('to-circle');
		});
	}

	function updateLayer() {
		var layer = $('.cd-section.modal-is-visible').find('.cd-modal-bg'),
			layerRadius = layer.width()/2,
			layerTop = layer.siblings('.btn').offset().top + layerRadius - $(window).scrollTop(),
			layerLeft = layer.siblings('.btn').offset().left + layerRadius,
			scale = scaleValue(layerTop, layerLeft, layerRadius, $(window).height(), $(window).width());
		
		layer.velocity({
			top: layerTop - layerRadius,
			left: layerLeft - layerRadius,
			scale: scale,
		}, 0);
	}

	function closeModal() {
		var section = $('.cd-section.modal-is-visible');
		section.removeClass('modal-is-visible').one('webkitTransitionEnd otransitionend oTransitionEnd msTransitionEnd transitionend', function(){
			animateLayer(section.find('.cd-modal-bg'), 1, false);
		});
		//if browser doesn't support transitions...
		if(section.parents('.no-csstransitions').length > 0 ) animateLayer(section.find('.cd-modal-bg'), 1, false);
	}
});