<!DOCTYPE html>
<html>
<title>编程狮(w3cschool.cn)</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://7npmedia.w3cschool.cn/w3.css">
<body>
<div class="w3-container w3-topbar w3-pale-red w3-border-red">
<h2>顶栏</h2>
<p>w3-topbar 类为元素添加了一个粗的右部边框(bar)</p>
</div>
</body>
</html>