效果图：
代码如下：
Title *{margin:0; padding:0; list-style:none;} ul{ overflow:hidden; width:630px; margin:100px auto;} ul li{ float:left; position:relative; width:200px; height:200px; background:#ccc; margin:5px; overflow:hidden;} ul li span{ position:absolute; width:100%; height:100%; background:rgba(255,0,0,0.3); left:-200px; top:0;}