效果图

<html ><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
#menu{ width:9em;
margin:0 auto;
font-family:Arial, Helvetica, sans-serif;
font-size:14px;
border:solid 1px #aaa;
}
#menu a,#menu a:visited{ display:block;
text-decoration:none;
color:#000;
line-height:1.4em;
height:1em;
border:0.5em solid #fff;}
#menu a:hover{ color:#fff;
background-color:#aaa;
border-left-color:#aaa;
border-right-color:#aaa;
border-top-color:#ddd;
border-bottom-color:#ddd;}
</style>
</head>

<body>
<div id="menu">
<a href="#">Home</a>
<a href="#">Contact Us</a>
<a href="#">Web Dev</a>
<a href="#">Web Design</a>
<a href="#">Map</a><div>
</body>
</html>