符合css规范的下拉菜单，兼容ff\ie6\ie7

<style>

body{font-size:12px; font-family:"宋体";margin:0;padding:0;}

#menu {height:29px!important;height:30px;line-height:29px;list-style-type: none;background:#B5DCF9;}

#menu a {display: block; width: 80px; text-align:center;}

#menu a:link {color:#000; text-decoration:none;}

#menu a:visited {color:#000;text-decoration:none;}

#menu a:hover {color:#FFF;text-decoration:none;font-weight:bold;}

#menu li {float: left; width: 80px; border-right:1px solid #fff;}

#menu li a:hover{background:#6699ff;}

#menu li ul {line-height: 25px; list-style-type: none;text-align:left;

left: -1860em; width: 180px; position: absolute;top:15px!important;top:29px;}

#menu li ul li{float: left; width: 130px;background: #6699ff;border-top:1px solid #fff}

#menu li ul a{display: block; width:120px!important;width: 130px;text-align:left;padding-left:10px;}

#menu li ul a:link {color:#fff; text-decoration:none;}

#menu li ul a:visited {color:#fff;text-decoration:none;}

#menu li ul a:hover {color:#000;text-decoration:none;font-weight:normal;background:#B5DCF9;}

#menu li:hover ul {left: auto;}

#menu li.sfhover ul {left: auto;}

#content {clear: left;}

</style>

<script type=text/javascript><!--//--><![CDATA[//><!--

function menuFix() {

var sfEls = document.getElementById("menu").getElementsByTagName("li");

for (var i=0; i<sfEls.length; i++) {

sfEls[i].onmouseover=function() {

this.className+=(this.className.length>0? " ": "") + "sfhover";

}

sfEls[i].onMouseDown=function() {

this.className+=(this.className.length>0? " ": "") + "sfhover";

}

sfEls[i].onMouseUp=function() {

this.className+=(this.className.length>0? " ": "") + "sfhover";

}

sfEls[i].onmouseout=function() {

this.className=this.className.replace(new RegExp("( ?|^)sfhover\\b"),

"");

}

}

}

window.onload=menuFix;

//--><!]]></script>

<div >网页基础</a>

</li>

</ul>

</li>

</div>