<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</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>可见性</h1>
<p>使用 .visible 或 .invisible 类可控制元素的可见性：</p>
<p><b>注释：</b>这些类不会更改 CSS display 值。它们只添加 visibility:visible 或 visibility:hidden。</p>
<div class="visible bg-success">我是可见的。</div>
<div class="invisible bg-warning">我是不可见的。</div>
</div>
</body>
</html>