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：
<!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>