Take web application offline in ASP.net MVC

While making changes or updating a web application we require to show a page that tells the end-user that the web application is under maintenance and won't be available for a while. To accomplish this requirement we add an Html page to the root directory of the web application named "App_offline.htm". 

This mainly helps us to show the end-user a user-friendly message instead of an ugly and flimsy error.  

Below is a code snippet of the contents for an "App_offline.htm" which is made using Bootstrap 3

<!doctype html>
<html>
<head>
    <title>Down for maintenance</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
    <style>
        .error-template {
            padding: 40px 15px;
            text-align: center;
            background-color:#efefef;
            margin-top: 50px;
        }

        .error-actions {
            margin-top: 15px;
            margin-bottom: 15px;
        }

            .error-actions .btn {
                margin-right: 10px;
            }
    </style>
</head>
<body marginwidth="0" marginheight="0">
    <div class="container">
        <div class="row">
            <div class="col-md-12">
                <div class="error-template">
                    <h1>
                        This site is currently down for maintenance
                    </h1>
                    <div class="error-details">
                        We will be back up and running as fast as possible. <br /> Sorry for the inconvenience.
                    </div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>

Download "App_offline.htm"