试试这个
http://jsfiddle.net/4jVtw/5/
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Horizontal Drop Down</title>
<script type="text/javascript" >
// JavaScript 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: 11px verdana;
}
ul {
border-bottom: 1px solid #CCCCCC;
list-style: none outside none;
margin: 0;
padding: 0;
width: 150px;
}
ul li {
position: relative;
}
li ul {
display: none;
left: 149px;
position: absolute;
top: 0;
}
ul li a {
-moz-border-bottom-colors: none;
-moz-border-left-colors: none;
-moz-border-right-colors: none;
-moz-border-top-colors: none;
background: none repeat scroll 0 0 #FFFFFF;
border-color: #CCCCCC #CCCCCC -moz-use-text-color;
border-image: none;
border-style: solid solid none;
border-width: 1px 1px 0;
color: #777777;
display: block;
padding: 5px;
text-decoration: none;
}
* html ul li {
float: left;
height: 1%;
}
* html ul li a {
height: 1%;
}
li:hover ul, li.over ul {
display: block;
}
</style>
</head>
<body>
<ul id="nav">
<li><a href="#">Dashboard</a></li>
<li><a href="#">Catalog</a>
<ul>
<li><a href="#">Attribute</a></li>
<li><a href="#">Attribute Group</a></li>
</ul>
</li>
</ul>
</body>
</html>