test.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>Test</title>

    <style>
      .boxx{
        position: absolute;
        width: 226px;
        height: 92px;
        left: 1000px;
        top: 200px;
      }

      .btn{
        margin-top: 10px;
      }

    </style>
  </head>
        <div class="boxx">
            <p>Want to book a seat?</p>
            <form name="f2" action="registration.php" method="POST">
                    <label>Enter BUS ID</label>
                    <br>
                    <input type="text" name="user" required />
                    <br>
                    <input type="submit" name="submit" value="Book" class="btn" />
                    <br>
            </form>
        </div>
  </body>
</html>