php $page definition and navigation

[jlfx]

On my site prestashop is in a subdirectory, so I have a main navigation that goes to different parts of the site, ir blog, events, shop, etc.

I typically use php to define the page at the very top of it...

<?php $page = 'press' ?>

This is then used in my navigation bar...

<?php if ($page == 'press') { ?>
Press
<?php } else { ?>
Press
<?php } ?>

etc.

and my css creates the nav bar with different backgrounds depending on link, no link, and hover.

This does not work with the shop directory that prestashop was in. I tried writing it to the top of the header.tpl, but it actually gets printed in the source code, just as text. I am not sure why the php is not getting read, since I have includes later in the header that actually write the external navigation bar. (the PS nav is used as a sub nav for the shopping section).

Is there someplace that I can define every prestashop page as $page = 'shop' via php so that my nav will show when you are in the shop section?

Does this make sense?