案例：CSS案例     状态：可编辑再运行    进入竖版
 运行结果　
​x
 
1
<html>
2
<head>
3
<style type="text/css">
4
.important {font-weight:bold;}
5
.warning {font-style:italic;}
6
.important.warning {background:silver;}
7
</style>
8
</head>
9
​
10
<body>
11
<p class="important">This paragraph is very important.</p>
12
​
13
<p class="warning">This is a warning.</p>
14
​
15
<p class="important urgent warning">This paragraph is a very important warning.</p>
16
​
17
<p>This is a paragraph.</p>
18
​
19
<p>...</p>
20
</body>
21
</html>
22
​