例子，纯CSS二级下拉菜单，没有用到JS，全部是CSS代码，拷贝即可使用。
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>CSS下拉菜单-www.jb200.com</title>
<style>
body{
background-color:white;
font-size:12px;
font-family:Arial, Helvetica, sans-serif;
margin:0px;
padding:0px;
color:white;
}
ul,li{
margin:0px;
padding:0px;
}
li{
display:inline;
list-style:none;
list-style-position:outside;
text-align:center;
font-weight:bold;
float:left;
}
a:link{
color:#336601;
text-decoration:none;
float:left;
width:100px;
padding:3px 5px 0px 5px;
}
a:visited{
color:#336601;
text-decoration:none;
float:left;
padding:3px 5px 0px 5px;
width:100px;
}
a:hover{
color:white;
float:left;
padding:3px 3px 0px 20px;
width:88px;
text-decoration:none;
background-color:#539D26;
}
a:active{
color:white;
float:left;
padding:3px 3px 0px 20px;
width:88px;
text-decoration:none;
background-color:#BD06B4;
}
#nav{
width:600px;
height:30px;
border-bottom:0px;
padding:0px 5px;
position:absolute;
z-index:1;
left: 198px;
top: 25px;
}
.list{
line-height:20px;
text-align:left;
padding:4px;
font-weight:normal;
}
.menu1{
width:120px;
height:auto;
margin:6px 4px 0px 0px;
border:1px solid #9CDD75;
background-color:#F1FBEC;
color:#336601;
padding:6px 0px 0px 0px;
cursor:hand;
overflow-y:hidden;
filter:Alpha(opacity=70);
-moz-opacity:0.7;
}
.menu2{
width:120px;
height:18px;
margin:6px 4px 0px 0px;
background-color:#F5F5F5;
color:#999999;
border:1px solid #EEE8DD;
padding:6px 0px 0px 0px;
overflow-y:hidden;
cursor:hand;
}
</style>
</head>
<body>
<div id="nav">
<ul>
<li class="menu2" onMouseOver="this.className='menu1'" onMouseOut="this.className='menu2'">网站首页<div class="list">
<a href="#">我的博客</a><br />
<a href="#">我的日志</a><br />
<a href="#">我的音乐</a><br />
</div>
</li>
<li class="menu2" onMouseOver="this.className='menu1'" onMouseOut="this.className='menu2'">社区圈子
<div class="list">
<a href="/jscss/">.NET圈子</a><br />
<a href="#">PHP圈子</a><br />
<a href="#">ASP圈子</a><br />
<a href="#">JAVA圈子</a><br />
</div>
</li>
<li class="menu2" onMouseOver="this.className='menu1'" onMouseOut="this.className='menu2'">论坛导航
<div class="list">
<a href="#">论坛首页</a><br />
<a href="#">技术论坛</a><br />
<a href="#">图片论坛</a><br />
</div>
</li>
<li class="menu2" onMouseOver="this.className='menu1'" onMouseOut="this.className='menu2'">账户管理
<div class="list">
<a href="#">我的帐号</a><br />
<a href="#">余额转移</a><br />
<a href="#">我的地盘</a><br />
</div>
</li>
</ul>
</div>
</body>
</html>