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> <style> span { display: inline-block; width: 70px; height: 70px; margin: 6px; background-color: #555; } </style> </head> <body> <div class="container"> <h2>边框圆角设置</h2> <p>使用rounded 类可以添加圆角边框:</p> <span class="rounded"></span> <span class="rounded-top"></span> <span class="rounded-right"></span> <span class="rounded-bottom"></span> <span class="rounded-left"></span> <span class="rounded-circle"></span> <span class="rounded-0"></span> </div> </body> </html>
运行结果