​x
 
<!DOCTYPE html>
<html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css">
</head>
<body>
​
<div class="container">
  <h2>Button</h2>
  <p>.btn-warning  该样式表示需要谨慎操作的按钮:</p>            
  <button type="button" class="btn btn-warning">Warning</button>
</div>
​
<script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="http://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script>
</body>
</html>