在关闭警报时，可以在Bootstrap中使用.fade类来添加褪色效果：
<!DOCTYPE html> <html> <head> <title>Bootstrap Example</title> <link href = "/bootstrap/css/bootstrap.min.css" rel = "stylesheet"> <script src = "/scripts/jquery.min.js"></script> <script src = "/bootstrap/js/bootstrap.min.js"></script> </head> <body> <div class = "container"> <h2>Eclipse Refactoring</h2> <div class = "alert alert-danger alert-dismissible fade in"> <a href = "#" class = "close" data-dismiss="alert" aria-label = "close">×</a> To refactor code in Eclipse, try the below given steps in the video (You can also close this alert) </div> </div> <div class = "container"> <div class = "embed-responsive embed-responsive-16by9"> <iframe class = "embed-responsive-item" src = "https://www.youtube.com/embed/YFVV6RAUnNg "></iframe> </div> </div> </body> </html>