(代码可运行)Bootstrap框架的HTML示例
Bootstrap：一套流行的前端开发框架，基于HTML、CSS和JavaScript，适用于快速构建响应式Web应用。
以下是一个使用Bootstrap构建的简单响应式Web应用的HTML示例：
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Bootstrap Example</title><!-- 引入Bootstrap CSS --><link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-KyZXEAg3QhqLMpG8r+Knujsl5/6en8XCp+HHAAK5GSLf2xlYtvJ8U2Q4U+9cuEnJoa3" crossorigin="anonymous">
</head>
<body><!-- 引入Bootstrap JavaScript --><script src="https://cdn.jsdelivr.net/npm/@popperjs/core@2.11.6/dist/umd/popper.min.js" integrity="sha384-oBqDVmMz4fnFO9gybBud7M4aw3bNrT5+2g0iY2z5MVzj5fcm7z5fQ9B4nD4gj5Y8" crossorigin="anonymous"></script><script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/js/bootstrap.min.js" integrity="sha384-cn7l7gDp0eyniUwwAZgrzD06kc/tftFf19TOAs2zVinnD/C7E91j9yyk5//jjpt/" crossorigin="anonymous"></script><div class="container"><h1 class="text-center mt-5">Hello, Bootstrap!</h1><div class="row mt-5"><div class="col-md-4"><div class="card"><img src="https://via.placeholder.com/150" class="card-img-top" alt="..."><div class="card-body"><h5 class="card-title">Card title</h5><p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p><a href="#" class="btn btn-primary">Go somewhere</a></div></div></div><div class="col-md-4"><div class="card"><img src="https://via.placeholder.com/150" class="card-img-top" alt="..."><div class="card-body"><h5 class="card-title">Card title</h5><p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p><a href="#" class="btn btn-primary">Go somewhere</a></div></div></div><div class="col-md-4"><div class="card"><img src="https://via.placeholder.com/150" class="card-img-top" alt="..."><div class="card-body"><h5 class="card-title">Card title</h5><p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p><a href="#" class="btn btn-primary">Go somewhere</a></div></div></div></div></div>
</body>
</html>
这个示例展示了一个简单的响应式布局，包括一个居中的标题和三个卡片组件。通过使用Bootstrap的栅格系统（.container、.row和.col-md-4等类）和卡片组件（.card、.card-body等类），可以快速构建一个美观且响应式的Web应用。请将这段代码复制到一个HTML文件中，并在浏览器中打开以查看效果。