a{font:14px microsoft yahei,Verdana, Arial;color:#505050;text-decoration: none}
#menu { width: 220px;  border-bottom:none;float:left;background:#eee}
/*1级*/
#menu ul { list-style: none; margin: 0px; padding: 0px; }
#menu ul li { background: #eee;  height:50px; line-height: 50px;text-align:center; font-size:16px;position:relative;margin-top:5px; }
#menu ul li:hover { background: #B8B8B8;  height:50px; line-height: 50px; position:relative; }


/*2级*/
#menu ul li ul { display:none; position: absolute; left: 220px;top: 0px; width:200px;margin-left:5px;background:#eee; }
#menu ul li ul li{position:relative;}
#menu ul li:hover #classtwo { display:block;}
#menu ul li:hover { background: #B8B8B8; }
/*3级*/
#menu ul li ul li ul{ display:none; position: absolute; left: 201px; top: 0px; width:200px;margin-left:0px;background:#eee}
#menu ul li ul li ul li{position:relative;}
#menu ul li ul li:hover ul{display:block;}