Add class based on dynamical url parameter (click and load)

I have a php script that allows me to dynamically load content on my page based on the url paramter. Also, I have .htaccess set up so the query string prefix is hidden, meaning they look like example.com/games/demons-souls/[?page=]mods.

[?page=] is hidden via .htaccess. So far, so good.

<?php

if (!empty($_GET["page"])

    && preg_match("/^[a-z]+$/i", $_GET["page"]) == 1

    && file_exists($pageFile = __DIR__ . "/subpages/" . $_GET["page"] . ".php")) {

    include $pageFile;

}

else {

    include __DIR__ . "/subpages/game.php";

}

?>

Now I wanted to show which page is active in a tabpanel, where the active tab is let’s say black. So I’d need to activate the class tab.current. And to do this I need to somehow make my code recognize which url paramter is loaded and dynamically add the .current class to the appropriate tab. I hope I could explain it well enough.

I haven’t got the slightest idea how to accomplish this.

Please help.