Did you ever try to put some PHP code inside your HTML page? It might work, it might not. It depends on your webserver settings. Usually you dont have access to this settings, but you can use .htaccess file to fix this problem. All you have to do is just to put this line into your .htaccess file:

AddType application/x-httpd-php .html

With this line your web server will interpret all your html files like they are php.