求助，网站导航栏样式js+css
<div id=site-nav>
<ul class=quick-menu>
<li class="services menu-item last">
<div class=menu>
<a id="a" class="menu-c" onclick="catalogClick('', '1','a')" target=_top>全部</a>
</div>
</li>
<li class="services menu-item last">
<div class="menu">
<a id="b" class="menu-hd" onclick="catalogClick('5', '1','b')" target=_top>下载</a>
</div>
</li>
<li class="services menu-item last">
<div class=menu>
<a id="c" class="menu-hd" onclick="catalogClick('2', '1','c')" target=_top>关注</a>
</div>
</li>
<li class="services menu-item last">
<div class="menu">
<a id="d" class="menu-hd" onclick="catalogClick('6', '1','d')" target=_top>评论</a>
</div>
</li>
<li class="services menu-item last">
<div class="menu">
<a id="e" class="menu-hd" onclick="catalogClick('3', '1','e')" target=_top>收藏</a>
</div>
</li>
<li class="services menu-item last">
<div class=menu>
<a id="f" class="menu-hd" onclick="catalogClick('4', '1','f')" target=_top>分享</a>
</div>
</li>
</ul>
</div>
#site-nav .menu-hd { PADDING:0px; DISPLAY: block; Z-INDEX: 10002; CURSOR: pointer; POSITION: absolute; HEIGHT:50px; line-height:40px; width:76px; margin:0;}
#site-nav .menu-c { PADDING:0px; DISPLAY: block; Z-INDEX: 10002; CURSOR: pointer; POSITION: absolute; HEIGHT:50px; line-height:40px; width:90px; background:url(img/catalog.png) no-repeat center top; margin:0;}
#site-nav .menu:hover .menu-hd { height:50px; width:90px; background:url(img/catalog.png) no-repeat center top;}function catalogClick(logType,pageCode,id) {
var obj = document.getElementsByTagName("a");
for(var i=0;i<obj.length;i++) {
if(obj[i].className == 'menu-c') {
obj[i].className = "menu-hd";
break;
}
}
id = trim(id);
var thisObj = document.getElementById(id);
eval(id).classsName="menu-c";
}
function trim(str) {
if (str == null) {
return "";
}
return str.replace(/^\s*(.*?)[\s\n]*$/g, "$1");
}