<svg width="0" height="0"> 
	<filter id="filter">
		<feTurbulence type="fractalNoise" baseFrequency=".01" numOctaves="6" />
		<feDisplacementMap in="SourceGraphic" scale="100" />
	</filter>
</svg>


<div class="wrapper">
	<div class="button _1">
		<span>hover</span><div class="back"></div>
	</div>
	<div class="button _2">
		<span>hover</span><div class="back"></div>
	</div>
	<div class="button _3">
		<span>hover</span><div class="back"></div>
	</div>
	<div class="button _4">
		<span>hover</span><div class="back"></div>
	</div>
</div>


<div class="support">
	<a href="https://twitter.com/DevLoop01" target="_blank"><i class="fab fa-twitter-square"></i></a>
	<a href="https://codepen.io/dev_loop/" target="_blank"><i class="fab fa-codepen"></i></a>
</div>

:root{
	--height: 100px;
	--width: 200px;
}

*{
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}
body{
	width: 100%;
	height: 100vh;
	background-image: linear-gradient(to right, #4facfe 0%, #00f2fe 100%);
	overflow: hidden;
	display: flex;
	justify-content: center;
	align-items: center;
	font-family: sans-serif;
}

.wrapper{
	width: calc(4 * var(--width));
	height: calc(4 * var(--height));
	display: flex;
	justify-content: center;
	align-items: center;
}

.button{
	position: relative;
	width: calc(0.8 * var(--width));
	height: calc(0.7 * var(--height));
	display: flex;
	justify-content: center;
	align-items: center;
	cursor: pointer;
	overflow: hidden;
	margin: 0 0.8rem;
	box-shadow: 0 2px 5px rgba(0,0,0,0.2), 0 3px 8px rgba(0,0,0,0.1);
	transition: all 0.3s cubic-bezier(0, 0.22, .3, 1);
	
	&:before{
		content: '';
		position: absolute;
		top: 0;
		left: 0;
		right: 0;
		bottom: 0;
		background: rgba(0,0,0,0.1);
	}

	span{
		color: #fff;
		font-size: 1rem;
		z-index: 10;
		text-transform: uppercase;
		letter-spacing: 2px;
	}

	&._1{ background: #2980b9 }
	&._2{	background: #8e44ad }
	&._3{	background: #16a085 }
	&._4{	background: #e74c3c }


	.back{
		position: absolute;
		width: 0;
		height: 0;
		filter: url(#filter);
		border-radius: 50%;
		z-index: 5;
		transition: all 2.5s cubic-bezier(0.1, 0.22, .3, 1);
	}

	&._1 .back{
		left: -50%;
		top: -50%;
		background: #27ae60;
	}
	&._2 .back{
		right: -50%;
		top: -50%;
		background: #c0392b;
	}
	&._3 .back{
		left: -50%;
		bottom: -50%;
		background: #34495e;
	}
	&._4 .back{
		right: -50%;
		bottom: -50%;
		background: #2980b9;
	}

	&:hover .back{
		width: calc(2 * var(--width));
		height: calc(2 * var(--height));
	}
}

@media only screen and (max-width: 750px) {
	.wrapper {
		flex-direction: column;
	}
	.button{
		margin: 0.8rem 0;
	}
}



.support{
	position: absolute;
	right: 10px;
	bottom: 10px;
	padding: 10px;
	display: flex;
}
a{
	margin: 0 20px;
	color: #fff;
	font-size: 2rem;
	transition: all 400ms ease;
}

a:hover{
	color: #222;
}