<!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">
<h2>简单的折叠</h2>
<p>单击按钮可在显示和隐藏内容之间切换。</p>
<button type="button" class="btn btn-primary" data-bs-toggle="collapse" data-bs-target="#demo">春日</button>
<div id="demo" class="collapse">
<p>胜日寻芳泗水滨，无边光景一时新。</p>
<p>等闲识得东风面，万紫千红总是春。</p>
</div>
</div>
</body>
</html>