We've pushed an update to the site's navbar in the articles section. The secondary navbar now not only shows the three categories (strategy & tactics, modding and history) but when you select on it will also show the subcategories for that category. This replaces the category selection just above the page title in the content area.
This should work on all browsers and operating system, but if you do find an issue please let us know. (Please include what browser and operating system you are using.)