<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.2/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.2/dist/js/bootstrap.bundle.min.js"></script>
</head>
<body>
<div class="container mt-3">
<h1>较小的辅助文本</h1>
<p>small 元素（和 .small 类）用于在任何标题中创建较小的辅助文本：</p>
<h1>h1 heading <small>secondary text</small></h1>
<h2>h2 heading <small>secondary text</small></h2>
<h3>h3 heading <small>secondary text</small></h3>
<h4>h4 heading <small>secondary text</small></h4>
<h5>h5 heading <small>secondary text</small></h5>
<h6>h6 heading <small>secondary text</small></h6>
</div>
</body>
</html>