css-提示消息

  <a href="#" class="tip">CSS<span class="popbox">Cascading sytle sheets 层叠样式表</span></a>

a.tip{
    color:red;
    text-decoration:none;
    position:relative;
}
a.tip span{display:none};
a.tip:hover{cursor:hand;}
a.tip:hover .popbox {
    display:block;
    position:absolute;
    top:15px;
    left:-30px;
    width:100px;
    background-color:#424242;
    color:#fff;
    padding:10px;
}