源代码 ：
点击运行
<!DOCTYPE html> <html> <head> <title>Bootstrap 实例</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css"> <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script> <script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script> <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script> </head> <body> <div class="container-fluid"> <h1>Hello World!</h1> <p>重置浏览器大小查效果。</p> <p> 在移动设备上，即屏幕宽度小于 576px 时，四个列将会上下堆叠排版。</p> <div class="row"> <div class="col-sm-3" style="background-color:lavender;">.col-sm-3</div> <div class="col-sm-3" style="background-color:lavenderblush;">.col-sm-3</div> <div class="col-sm-3" style="background-color:lavender;">.col-sm-3</div> <div class="col-sm-3" style="background-color:lavenderblush;">.col-sm-3</div> </div> </div> </body> </html>
运行结果