<style type="text/css">
<!--
.thumbnail{position:relative;z-index:0;}
.thumbnail:hover{background-color:transparent;z-index:50;}
.thumbnail span{position:absolute;background-color:#FFFFE0;left:-1000px;border:1px dashed gray;visibility:hidden;color:#000;text-decoration:none;padding:5px;}
.thumbnail span img{border-width:0;padding:2px;}
.thumbnail:hover span{visibility:visible;top:-30px;left:60px;}
p{margin-top:200px}
-->
</style>
<p><a class="thumbnail" href="http://www.mamicode.com/#">文字<span><img src="http://www.mamicode.com/图片链接" /></span></a></p>