问下拉菜单3级(水平，然后是2个垂直)

EN

<div id="menu">
    <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">Executive Summary</a></li>
        <li><a href="#" > Visual Analytics</a></li> 
        <li><a href="#" >Settings</a>
            <ul>                                      
                <li><a href="#" >Manage Subject</a></li>
                    <ul>
                        <li><a href="#">Add Subject</a></li>
                        <li><a href="#">Edit Subject</a></li>
                        <li><a href="#">Delete Subject</a></li>
                        <li><a href="#">Export Subject</a></li>
                    </ul>
                <li><a href="#">Manual Crawl</a></li>
                <li><a href="#">Crawl Interval</a></li> 
                <li><a href="#">Archive List</a></li>
            </ul>
        </li>
    </ul>
</div>

 #menu {
    position: relative;
    float: left;
    width: 1200px;
    height: 35px;
    font-family: Arial, Helvetica, sans-serif; 
    font-size: 13px;
    padding: 0;    
    background-color:#000;
    text-align: center;
    z-index:1;
}

#menu ul {
    position: relative;
    list-style: none;
    display: inline-block;
    margin: 0;
    padding: 0;
}

#menu ul li {
    position: relative;
    float: left;
    height: 100%;
    padding: 0;
    line-height: 35px; 
}

#menu ul li a {
    position: relative;
    height: 100%; 
    width: auto;
    float: left;
    text-decoration: none;
     padding: 0px 10px 0px 10px;   
    margin: 0 3px;
    color: #fff;
    text-align: center;
}

#menu ul li ul {
   display: none;
   width: 150px; /* Width to help Opera out */
   background-color: rgba(0,0,0,0.5);
}

#menu ul li:hover ul {
    display:block;
   position: absolute;
   top: 35px;
   left: 0;
   margin: 0;
   padding: 0;
   z-index: 1;
   width:150px; 
}

#menu li li a{
    height: 35px; 
    width: 150px;
    float: left;
    text-decoration: none;
    padding: 0px; 
    margin: 0 0px;
    color: #fff;
    text-align: center;
}

#menu ul li ul li a:hover{
   background: rgba(255,255,255,0.5);
   width:150px;
   float:left;
}
#menu ul li ul li ul{ display:none; position:absolute;background-color:rgba(28,28,240,0.5);}
#menu ul li ul li:hover ul { display:block; position:absolute; top:0px;background-color:#fff;}
#menu ul li ul li:hover ul li { list-style:none; float:none; margin-left:1px; padding:0px; position:relative;background-color:#fff;}
#menu ul li ul li ul li a:hover{
   background-color: rgba(28,28,240,0.5);
   width:150px;
   float:left;
}​