Do you mean the row near the top, with a second row of “menu entries” directly below it? Yeah, but that isn’t really a CSS effect or anything. The “trick” if you will is that on top category pages (the links in the first row) and all pages of that category, they put the respective menu in the second row, to make it consistent. Giving the current tab on the top row the same color as the second row (e.g. by assigning it an extra class like .here, that’s what I would do) gives it that tab effect.
If you make something like that, you could improve on it a bit by also slightly marking the currently viewed page in the submenu, that’s always a nice touch :)