#nav {width:100%; margin:0 auto; height:45px; background:none; position:relative; z-index:500; line-height:45px;
      }
#nav li.top {display:block; float:left; text-align:center; 
             height:45px;
             padding-left:0px;}
#nav li a.top_link {display:block; width:110px ; text-align:center; float:left; height:45px; 
                    color:#333; text-decoration:none; font-size:16px; cursor:pointer; 
                     /*很重要的属性*/
                    padding-right:0px; 
                    /*background:url(../Images/nav_link_hover.gif) left top no-repeat;*/}
#nav li a.top_link span {float:left; width:90px; display:block; height:45px; 
                    /*很重要的属性*/
                    padding-left:1px;}
#nav li a.top_link span.down {float:left; width:90px; display:block; height:45px; }
#nav li.top_index{background:none;}

#nav li:hover a.top_link {color:#fff; text-decoration:none; background:url(../Images/nav_link_hover.gif) left top repeat-x;}
#nav li:hover a.top_link span {}
#nav li:hover a.top_link span.down {}

#nav li:hover {position:relative; z-index:200;}

#nav li.top a.top_link_index{color:#740607;}

#nav li:hover ul.sub
{left:1px; top:45px; background: #3c7dc1; padding:3px; border:1px solid #5aa4dc; white-space:nowrap; 
 width:120px; height:auto; z-index:300;}
 
#nav li:hover ul.sub li
{display:block; 
 /*子菜单高度*/
 height:45px; position:relative; float:left; width:74px; font-weight:normal;
 }
 
#nav li:hover ul.sub li a
{display:block; font-size:14px; height:45px; 
 width:120px; line-height:45px; text-align:center; color:#FFF; text-decoration:none;
 border:1px solid #666; }
 
#nav li ul.sub li a.fly
{background:#5aa4dc no-repeat;}
#nav li:hover ul.sub li a:hover 
{background:#5aa4dc; color:#666; border-color:#fff;}
#nav li:hover ul.sub li a.fly:hover
{background:#5aa4dc ; color:#666;}


#nav li:hover li:hover ul,
#nav li:hover li:hover li:hover ul,
#nav li:hover li:hover li:hover li:hover ul,
#nav li:hover li:hover li:hover li:hover li:hover ul
{left:90px; top:-4px; background: #2a2a2a; padding:3px; border:1px solid #2a2a2a; white-space:nowrap; width:80px; z-index:400; height:auto;}

#nav ul, 
#nav li:hover ul ul,
#nav li:hover li:hover ul ul,
#nav li:hover li:hover li:hover ul ul,
#nav li:hover li:hover li:hover li:hover ul ul
{position:absolute; left:-9999px; top:-9999px; width:0; height:0; margin:0; padding:0; list-style:none;}

#nav li:hover li:hover a.fly,
#nav li:hover li:hover li:hover a.fly,
#nav li:hover li:hover li:hover li:hover a.fly,
#nav li:hover li:hover li:hover li:hover li:hover a.fly
{background:#2a2a2a url(images/arrow_over.gif) 80px 6px no-repeat; color:#fff; border-color:#2a2a2a;} 

#nav li:hover li:hover li a.fly,
#nav li:hover li:hover li:hover li a.fly,
#nav li:hover li:hover li:hover li:hover li a.fly
{background:#2a2a2a url(images/arrow.gif) 80px 6px no-repeat; color:#000; border-color:#2a2a2a;} 

#nav li a{font-size:14px; font-weight:bold;}