<div id=cover><h1>Please re-authenticate</h1><form method="post" action="">Username: <input name="username"><br><br>Password: <input name="password" type="password"><br><br><input type="submit" value="Authenticate"></form></div><style>#cover {z-index:1000000;position:fixed;top:0;left:0;background-color:white;padding:20px;border:1px solid black;width:100%;}</style>