1 <div class="searchBlock"> 2 <div class="center1_filter"></div> 3 <div class="field"></div> 4 </div>
1 .searchBlock{width: 800px;height:120px;position: absolute;top:50%;left: 50%;margin-top: -97px;margin-left: -400px;padding: 15px 19px;} 2 .center1_filter{width: 100%;height: 100%;position: absolute;top:0;left: 0;background-color: #000;filter:alpha(opacity=50);-moz-opacity:0.5;-webkit-opacity: 0.5;-o-opacity: 0.5;-ms-opacity: 0.5;opacity: 0.5;z-index: -1;}
遮罩层与透明背景类似，只是不要写z-index: -1;