.html代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
2 <html xmlns="http://www.w3.org/1999/xhtml">
3 <head>
4 <title>CSS Box Model</title>
5 <style type="text/css">
6 body
7 {
8 background: #333;
9 }
10 div
11 {
12 height: 240px;
13 width: 360px;
14 border: 5px solid yellow;
15 background: blue;
16 margin: 0 auto;
17 }
18 span
19 {
20 display: block;
21 width: 50%;
22 height: 50%;
23 background: red;
24 border: 5px solid yellow;
25 color: White;
26 font-size: 14px;
27 font-weight: bold;
28 margin: auto;
29 margin-top: 60px;
30 line-height: 120px;
31 text-align: center;
32 vertical-align: middle;
33 }
34 </style>
35 </head>
36 <body>
37 <div>
38 <span>Box Model的内容</span>
39 </div>
40 </body>
41 </html>
效果如下：
