源代码 ：
点击运行
<!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/4.3.1/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/1.15.0/umd/popper.min.js"></script> <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/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>
运行结果