<style type="text/css">.thumbnail{position:relative;z-index:0;}
.thumbnail:hover{background-color:transparent;z-index:50;}
.thumbnail span{position:absolute;background-color:#f9f9f9;padding:5px;left:-1000px;border:1px solid #ccc;visibility:hidden;color:gray;text-decoration:none;}
.thumbnail span img{border-width:0;padding:2px;}
.thumbnail:hover span{visibility:visible;top:233px;left:345px;}
</style>