用CSS和JS制作的下拉菜单

<script language="javascript">
// <a class="channel_keylink" href="" target="_blank">Java</a>Script Document
startList = function() {
if (document.all&&document.getElementById) {
navRoot = document.getElementById("nav");
for (i=0; i<navRoot.childNodes.length; i++) {
node = navRoot.childNodes[i];
if (node.nodeName=="LI") {
node.onmouseover=function() {
this.className+=" over";
 }
 node.onmouseout=function() {
 this.className=this.className.replace(" over", "");
 }
 }
 }
 }
}
window.onload=startList;
</script>
<style type="text/css">
<!--
body {
  font: normal 11px verdana;
  }
ul {
  margin: 0;
  padding: 0;
  list-style: none;
  width: 150px; /* Width of Menu Items */
  border-bottom: 1px solid #ccc;
  }
 
ul li {
  position: relative;
  }
 
li ul {
  position: absolute;
  left: 149px; /* Set 1px less than menu width */
  top: 0;
  display: none;
  }
/* Styles for Menu Items */
ul li a {
  display: block;
  text-decoration: none;
  color: #777;
  background: #fff; /* IE6 Bug */
  padding: 5px;
  border: 1px solid #ccc; /* IE6 Bug */
  border-bottom: 0;
  }
 
/* Holly Hack. IE Requirement */
* html ul li { float: left; height: 1%; }
* html ul li a { height: 1%; }
/* End */
li:hover ul, li.over ul { display: block; } /* The magic */
-->
</style>
<ul id="nav">
 <li><a href="#">Home</a></li>
 <li><a href="#">About</a>
 <ul>
 <li><a href="#">History</a></li>
 <li><a href="#">Team</a></li>
 <li><a href="#">Offices</a></li>
 </ul>
 </li>
 <li><a href="#">Services</a>
 <ul>
 <li><a href="#">Web Design</a></li>
 <li><a href="#">Internet Marketing</a></li>
 <li><a href="#">Hosting</a></li>
 <li><a href="#">Domain Names</a></li>
 <li><a href="#">Broadband</a></li>
 </ul>
 </li>
 <li><a href="#">Contact Us</a>
 <ul>
 <li><a href="#">United Kingdom</a></li>
 <li><a href="#">France</a></li>
 <li><a href="#">USA</a></li>
 <li><a href="#">Australia</a></li>
 </ul>
 </li>
</ul>