使用Bootstrap垂直堆叠选项卡
使用Bootstrap中的.nav-stacked类垂直堆叠选项卡，
您可以尝试运行以下代码来实现.nav-stacked类减号。
示例
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap Example</title>
<link rel = "stylesheet" href = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src = "https://cdn.staticfile.org/jquery/3.3.1/jquery.min.js"></script>
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
<div class = "container">
<h2>Database</h2>
<p>The following are the database technologies:</p>
<ul class = "nav nav-tabs nav-stacked" role = "tablist">
<li class = "active"><a href = "#">DB2</a></li>
<li><a href = "#">MySQL</a></li>
<li><a href = "#">SQL</a></li>
<li><a href = "#">CouchDB</a></li>
</ul>
</div>
</body>
</html>