怎么没效果呀？
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<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>我的网站</title>
<style>
*{margin:0;padding:0;font-size:14px;}
ul{list-style:none;height:50px;padding-left:30px;border-bottom:5px solid #F60;}
li{float:left;margin-top:20px;}
a{text-decoration:none;display:block;height:30px;line-height:30px;width:120px;background-color:#ccc;margin-bottom:1px;text-align:center; }/* 删除下划线和文本缩进 */
.on,a:hover{color:#fff;background:#F60;height:30px;line-height:30px;}
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<script>
window.onload=function(){
var aA=document.getElementsByTagName('a');
for(var i=0;i<aA.length;i++){
aA[i].onmouseover=function(){
clearInterval(This.time)
var This=this;
This.time=setInterval(function(){
This.style.width=This.offsetWidth+8+"px";
if(This.offsetWidth>=160){
clearInterval(This.time)
}
},30)
}
}
aA[i].onmouseout=function(){
clearInterval(This.time)
var This=this;
This.time=setInterval(function(){
This.style.width=This.offsetWidth-8+"px";
if(This.offsetWidth<=120){
This.style.width="120px";
clearInterval(This.time)
}
},30)
}
}
</script>
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<ul>
<li><a class="on" href="#">首 页</a>
<li><a href="#">新闻快讯</a>
<li><a href="#">产品展示</a>
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