.dropdown{
float:left;
width:100px;
height:34px;
margin:0;
}
.dropdown dt { height:34px;}
.dropdown dt:hover {background:url(../images/menu_knowledge2.gif) no-repeat left bottom;}
.dropdown dd{
margin:0;
position:absolute; 
overflow:hidden; 
width:100px; 
display:none;
background:#F9F9F9; 
z-index:200;
}
.smenu{
float:left;
width:100px;
height:auto;
line-height:20px;
text-align:center;
color:#333;
margin:3px 0;
}
.smenu a{color:#000; text-decoration:none;}
.smenu a:hover{color:#901641; text-decoration:none;}
.dropdown a, .dropdown a:active, .dropdown a:visited { width:100px; display:block;}
.dropdown a:hover {background:#901641; color:#fff;}