实用的多级树形展开菜单
body{margin:0;padding:0;font:12px/1.5 Tahoma,Helvetica,Arial,sans-serif;}
ul,li,{margin:0;padding:0;}
ul{list-style:none;}
#root{margin:10px;width:200px;overflow:hidden;}
#root li{line-height:25px;}
#root .rem{padding-left:16px;}
#root .add{background:url(/upload/201010/2010103121304113