使用border-danger类为元素设置红色边框。
将border-danger类设置为一个元素,就像我们包含其他任何类一样:
<div class="new border border-danger"> Red Border </div>
上面,我们还设置了另一个“ new”类来设置元素的样式-
<style> .new { width: 120px; height: 120px; margin: 20px; } </style>
您可以尝试运行以下代码来实现border-danger类-
<!DOCTYPE html> <html lang="en"> <head> <title>Bootstrap Example</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/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/4.1.0/js/bootstrap.min.js"></script> <style> .new { width: 120px; height: 120px; margin: 20px; } </style> </head> <body> <div class="container"> <p>Rectangle with red border:</p> <div class="new border border-danger">Red Border</div> </div> </body> </html>