<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>Bootstrap 实例 - 居中内容块</title>
        <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">  
        <script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
        <script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>
    </head>
    <body>

        <div class="row">
            <div class="center-block" style="width:200px;background-color:#ccc;">
                这是 center-block 实例
            </div>
        </div>

    </body>
</html>