在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap 实例</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.1.0/css/bootstrap.min.css">
  <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdn.staticfile.org/popper.js/1.12.5/umd/popper.min.js"></script>
  <script src="https://cdn.staticfile.org/twitter-bootstrap/4.1.0/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <h1>h1 Bootstrap 标题 (2.5rem = 40px)</h1>
  <h2>h2 Bootstrap 标题 (2rem = 32px)</h2>
  <h3>h3 Bootstrap 标题 (1.75rem = 28px)</h3>
  <h4>h4 Bootstrap 标题 (1.5rem = 24px)</h4>
  <h5>h5 Bootstrap 标题 (1.25rem = 20px)</h5>
  <h6>h6 Bootstrap 标题 (1rem = 16px)</h6>
</div>

</body>
</html>
源代码

动行结果
