sayantanHack/index.html

## index.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Best Hover Button</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <button class="glow-on-hover" type="button">HOVER ME, THEN CLICK ME!</button>
</body>
</html>


## style.css
html,
body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
    background: #000;
}

.glow-on-hover {
    width: 220px;
    height: 50px;
    border: none;
    outline: none;
    color: #fff;
    background: #111;
    cursor: pointer;
    position: relative;
    z-index: 0;
    border-radius: 10px;
}

.glow-on-hover:before {
    content: '';
    background: linear-gradient(45deg, #ff0000, #ff7300, #fffb00, #48ff00, #00ffd5, #002bff, #7a00ff, #ff00c8, #ff0000);
    position: absolute;
    top: -2px;
    left:-2px;
    background-size: 400%;
    z-index: -1;
    filter: blur(5px);
    width: calc(100% + 4px);
    height: calc(100% + 4px);
    animation: glowing 20s linear infinite;
    opacity: 0;
    transition: opacity .3s ease-in-out;
    border-radius: 10px;
}

.glow-on-hover:active {
    color: #000
}

.glow-on-hover:active:after {
    background: transparent;
}

.glow-on-hover:hover:before {
    opacity: 1;
}

.glow-on-hover:after {
    z-index: -1;
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background: #111;
    left: 0;
    top: 0;
    border-radius: 10px;
}

@keyframes glowing {
    0% { background-position: 0 0; }
    50% { background-position: 400% 0; }
    100% { background-position: 0 0; }
}
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Best Hover Button</title>
	<link rel="stylesheet" href="style.css">
	</head>
	<body>
	<button class="glow-on-hover" type="button">HOVER ME, THEN CLICK ME!</button>
	</body>
	</html>
	html,
	body {
	margin: 0;
	padding: 0;
	width: 100%;
	height: 100vh;
	display: flex;
	flex-direction: row;
	justify-content: center;
	align-items: center;
	background: #000;
	}

	.glow-on-hover {
	width: 220px;
	height: 50px;
	border: none;
	outline: none;
	color: #fff;
	background: #111;
	cursor: pointer;
	position: relative;
	z-index: 0;
	border-radius: 10px;
	}

	.glow-on-hover:before {
	content: '';
	background: linear-gradient(45deg, #ff0000, #ff7300, #fffb00, #48ff00, #00ffd5, #002bff, #7a00ff, #ff00c8, #ff0000);
	position: absolute;
	top: -2px;
	left:-2px;
	background-size: 400%;
	z-index: -1;
	filter: blur(5px);
	width: calc(100% + 4px);
	height: calc(100% + 4px);
	animation: glowing 20s linear infinite;
	opacity: 0;
	transition: opacity .3s ease-in-out;
	border-radius: 10px;
	}

	.glow-on-hover:active {
	color: #000
	}

	.glow-on-hover:active:after {
	background: transparent;
	}

	.glow-on-hover:hover:before {
	opacity: 1;
	}

	.glow-on-hover:after {
	z-index: -1;
	content: '';
	position: absolute;
	width: 100%;
	height: 100%;
	background: #111;
	left: 0;
	top: 0;
	border-radius: 10px;
	}

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