gistfile1.html

<style>
#forkongithub
a {
	background: rgb(255, 0, 0);
	color: #fff;
	text-decoration: none;
	font-family: arial, sans-serif;
	text-align: center;
	font-weight: bold;
	padding: 5px 40px;
	font-size: 1rem;
	line-height: 2rem;
	position: relative;
	transition: 0.5s;
}
 
#forkongithub
a:hover {
	background: rgb(221, 0, 33);
	color: #fff;
}
 
#forkongithub
a::before,#forkongithub
a::after {
	content: "";
	width: 100%;
	display: block;
	position: absolute;
	top: 1px;
	left: 0;
	height: 1px;
	background: #fff;
}
 
#forkongithub 
a::before {
	bottom: 1px;
	top: auto;
}
 
@media screen and (min-width:800px) {
	#forkongithub {
		position: absolute;
		display: block;
		top: 0;
		left: 0;
		width: 200px;
		overflow: hidden;
		height: 200px;
	}
	#forkongithub
a {
		width: 200px;
		position: absolute;
		top: 60px;
		left: -60px;
		transform: rotate(-45deg);
		-webkit-transform: rotate(-45deg);
		box-shadow: 2px 2px 10px rgba(0, 0, 0, 0.8);
	}
}
</style>
<span id="forkongithub"><a
	href="https://github.com/codepo8/css-fork-on-github-ribbon">Fork me
		on GitHub</a></span>