HTML:
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<link type="text/css" rel="stylesheet" href="/index.css">
</head>
<body>
<a href="#foo" id="link">Click Here</a>
</body>
</html>
CSS:
#link {
display : block;
width: 400px;
height: 400px;
background: #BADA55;
border-radius: 200px;
text-align: center;
line-height: 400px;
}