*{margin:0;padding:0;}
ul{width:984px;}
li{float:left;width:318px; margin-right:10px;height:343px; position:relative;}
img{width:318px;height:343px;}
.main{width:100%;height:100%;position:absolute; top:0 ;left:0; z-index:0;}
.text{ width:318px;height:56px; line-height:56px; text-align:center;position:absolute; top:45% ;left:-318px;  z-index:9; background-color:#000;color:#fff; font:'微软雅黑'; display:none;}
.opacity_layer{background-color:#000; opacity:0.5; }