index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
    <script src="script.js"></script>
    <style>
        .container {
            border: 1px solid black;
            width: 40%;
            position: fixed;
            top: 50%;
            left: 50%;
            /* bring your own prefixes */
            transform: translate(-50%, -50%);
        }

        /* .row{
            border: 1px solid black;
        } */
        .form-group {
            padding: 20px 90px;
            margin: auto;
        }

        label,
        input {
            font-size: 20px;
        }

        button {
            margin-left: 250px;
        }
    </style>
</head>

<body>
    <div class="container bg-faded">
        <form name="form1">
            <div class="form-group">
                <label> Username : </label>
                <input type="text" class="form-control" placeholder="Type ur username" id="username" name="user">
            </div>
            <div class="form-group">
                <label>Password : </label>
                <input type="password" class="form-control" id="pwd" name="password">
            </div>
            <button type="submit" name="submit" onclick="validate()">Sign in</button>

        </form>
    </div>

    
</body>

</html>