Bootstrap 元素
Bootstrap中的<small>元素用于设置内联子标题。
您可以尝试运行以下代码来实现<small>元素：
示例
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap small element</title>
<meta name = "viewport" content = "width = device-width, initial-scale = 1">
<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>
<h1>Heading One
<small>I'm secondary Heading</small>
</h1>
<h2>Heading One
<small>I'm secondary Heading</small>
</h2>
</body>
</html>