css背景透明子元素不透明

 1 <head>
 2 <meta charset="utf-8"/>
 3 
 4 <style>
 5 body{
 6 position:relative;
 7 }
 8 #parent{
 9   position:absolute;
10   top:50px;
11   left:50px;
12   background-color:red;
13   opacity:0.5;
14   filter:Alpha(opacity=50);/*IE+兼容*/
15   width:500px;
16   height:300px;
17   color:#fff;
18 }
19  #child{
20   position:absolute;
21   top:0px;
22   left:0px;
23   background-color:#000;
24   color:#fff;
25   width:200px;
26   height:100px;
27 }
28 </style>
29 </head>
30 <body>
31   <div id="parent">
32   父元素
33     <div id="child">
34       子元素
35     </div>
36   </div>
37 </body>

注：opacity:0.1-1指-moz和webkit浏览器

  filter:Alpha(opacity=50);/*IE+兼容*/
在css中层就想ps中的图层，z-index值得大小就如ps中图层的上下位置

if you don't try,you will never know!