Css下拉菜单

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<style>
ul {
    margin: 0px;
    padding: 0px;
}
ul li {
    float: left;
    display: inline;
    font: 0.9em Arial, Helvetica, sans-serif;
    height: 30px;
    100px;
    list-style: none;
}
ul li a {
    color: #FFF;
    text-decoration: none;
    line-height: 29px;
    91px;
    margin: 0px;
    padding: 0px 0px 0px 8px;
    display: block;
    border-right: solid 1px #ccc;
    border-bottom:solid 1px #ccc;
    background: #808080;
}
ul li ul li { height:25px; }
ul li ul li a {
    background: #666;
    line-height:24px;
}
ul li a:hover { background: #666; }
ul li ul { visibility: hidden; }
ul li:hover ul { visibility: visible; }
ul li ul li a:hover { background: #333; }
</style>
</HEAD>