在线运行代码 - 代码学院 www.codexy.cn

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> 
<title>代码学院(codexy.cn)</title> 
<style> 
p:first-of-type
{
	background:#ff0000;
}
</style>
</head>
<body>

<h1>This is a heading</h1>
<p>The first paragraph.</p>
<p>The second paragraph.</p>
<p>The third paragraph.</p>
<p>The fourth paragraph.</p>

</body>
</html>

源代码

动行结果