一个按钮

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style type="text/css">
#menu a, #menu a:visited {
position:relative;
text-decoration:none;
text-align:center;
background-color:#9ab;
color:#fff;
display:block;
width:10em;
border:2px solid #fff;
border-color:#def #678 #345 #cde;
padding:0.25em;
margin:0.5em auto;
}

#menu a:hover {
top:2px;
left:2px;
color:#fff;
border-color:#345 #cde #def #678;
}
</style>
</head>

</body>
</html>