Why you do not muve to a solution like this one.... I did
(1) make your index.html / change in index.php
(2) make your base.html / change in base.php
(3) make your menu.html / change in menu.php
Then merge all inside your index.php adding this
<?php include ("menu.php"); ?>
<?php include ("base.php"); ?>
Very easy to manage also later as you need to modify just a little to change all website.