在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8"> 
	<title>菜鸟教程(cainiaoplay.com)</title>
	<link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">  
	<script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
	<script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
	<h2>实例</h2>
	<p> .close 类可以显示一个关闭按钮。</p>
	<button type="button" class="close"><span aria-hidden="true">x</span><span class="sr-only">关闭</span></button>
</div>

</body>
</html>
源代码

动行结果
