代码示例：（标识：bs_button_outline）
<!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.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.2/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.2/js/bootstrap.min.js"></script>
</head>
<body>
<div style="padding:20px;">
<h2>按钮轮廓</h2>
<button type="button" class="btn btn-outline-primary">主要</button>
<button type="button" class="btn btn-outline-secondary">次要</button>
<button type="button" class="btn btn-outline-success">成功</button>
<button type="button" class="btn btn-outline-info">信息</button>
<button type="button" class="btn btn-outline-warning">警告</button>
<button type="button" class="btn btn-outline-danger">危险</button>
<button type="button" class="btn btn-outline-dark">深色</button>
<button type="button" class="btn btn-outline-light text-dark">浅色</button>
</div>
</body>
</html>
