<div class="block"></block>
body {
	margin: 0;
	padding: 0;
	background-color: #000;
}

.block {
	position: relative;
	margin: 300px auto 0;
	width: 500px;
	height: 250px;
	background: linear-gradient(0deg, #000, #272727);
}

.block:before, .block:after {
	content: '';
	position: absolute;
	left: -2px;
	top: -2px;
	background: linear-gradient(45deg, #fb0094, #0000ff, #00ff00,#ffff00, #ff0000, #fb0094, 
		#0000ff, #00ff00,#ffff00, #ff0000);
	background-size: 400%;
	width: calc(100% + 4px);
	height: calc(100% + 4px);
	z-index: -1;
	animation: steam 20s linear infinite;
}

@keyframes steam {
	0% {
		background-position: 0 0;
	}
	50% {
		background-position: 400% 0;
	}
	100% {
		background-position: 0 0;
	}
}

.block:after {
	filter: blur(50px);
}
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