1 <!DOCTYPE html>
2 <html>
3 <head>
4 <meta charset="utf-8">
5 <title></title>
6 <style type="text/css">
7 div{
8 width: 300px;
9 height: 300px;
10 }
11 .box{
12 margin: 100px auto;
13 position: relative;
14 }
15 .content{
16 position: absolute;
17 background-color: blue;
18 left: -6px;
19 top: -6px;
20 z-index: 2;
21 }
22 .mark{
23 position: absolute;
24 background-color: black;
25 right: -6px;
26 bottom: -6px;
27 z-index: 1;《定位级》
28 opacity: 0.5;
29 }
30 </style>
31 </head>
32 <body>
33 <div class="box">
34 <div class="content"></div>
35 <div class="mark"></div>
36 </div>
37 </body>
38 </html>
