"A fractal of kiosk design" - https://www.stickmanventures.com/blog/2014/02/26/fractal-kiosk-design/

sample.php

<?php
session_start ();

if (isset ( $_SESSION ['sess_user_id'] ) && isset ( $_SESSION ['sess_username'] )) {
    header ( "Location: /home" );
    exit ();
}
?>

... Begin HTML ...

<?php include $_SERVER['DOCUMENT_ROOT'] . '/../includes/templates/top_reqs.php'; ?>

... Begin toplevel div ...

<?php include $_SERVER['DOCUMENT_ROOT'] . '/../includes/templates/header.php'; ?>

... Construct the form ...
... End the toplevel div ...

<?php include $_SERVER['DOCUMENT_ROOT'] . '/../includes/templates/footer.php'; ?>

... End displayed content ...

<?php include $_SERVER['DOCUMENT_ROOT'] . '/../includes/templates/bottom_reqs.php'; ?>

<script type="text/javascript">$(document).ready(function() {KIOSK.base.initLogin();});</script>

... End HTML ...