要在浅灰色的按钮上设置轮廓，需要在Bootstrap中使用btn-outline-light类。
将该类用作-
<button type="button" class="btn btn-outline-light"> Sample </button>
您可以尝试运行以下代码以实现btn-outline-light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> </head> <body> <h2>Demo Button</h2> <p>A light colored button is visible below:</p> <button type="button" class="btn btn-outline-light"> Sample </button> </body> </html>