【a】
<!DOCTYPE html>
<html>
<head>
<style type='text/css'>
#backbutton {
display: block;
width: 100px;
height: 100px;
background: red;
}
#backbutton:hover {
background: cyan;
}
#backbutton:active {
background: blue;
}
</style>
</head>
<body>
<a id="backbutton" href=""></a>
</body>
</html>
