使用CSS和JavaScript实现的导航菜单

/*全局样式*/
*{font-size:12px;}
body{margin:0;padding:0;background-color:#FFFFFF;
font-size:12px;color:#666666;
font-family: "宋体",Arial, Helvetica, sans-serif;}
/*主导航菜单*/
#menu ul{padding:0;border:0;list-style:none;
line-height:150%;margin-top: 0;margin-right: 0;
margin-bottom: 0;margin-left: 15px;}
#menu_out{width:966px;padding-left:4px;
margin-left:auto;margin-right:auto;
background:url(menu_left.gif) no-repeat left top;}
#menu_in{
background:url(menu_right.gif) no-repeat right top;
padding-right:4px;}
#menu{background:url(menu_bg.gif) repeat-x;
height:73px;}
.menu_line{
background:url(menu_line.gif) no-repeat center top;
width:8px;}
.menu_line2{
background:url(menu_line2.gif) no-repeat center top;
width:15px;}
#nav{padding-left:20px;}
#nav li{float:left;height:35px;}
#nav li a{float:left;display:block;
padding-left:6px;height:35px;
background:url(menu_on_left.gif) no-repeat left top;
cursor:pointer;text-decoration:none;}
#nav li a span{float:left;padding:11px 14px 10px 10px;