简单教程
提交运行
代码编辑器：
<!DOCTYPE html> <meta charset="utf-8"> <link href="/static/next/css/tryit.css?v=2017082407" rel="stylesheet"/> <style> p:nth-child(2) { background:#ff0000; } </style> <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> <p><b>注意:</b> Internet Explorer 8 以及更早版本的浏览器不支持 :nth-child()选择器.</p> <footer>简单教程，简单编程<br/>Copyright © 简单教程 www.twle.cn</footer>
运行结果：