Text too big in header... Help Please.

[SOUL HACK]

Ok I have a website, and I have a HTML header design that I already installed into vbulletin... But for some strange reason, the text links are bigger than they are supposed to be (which messes up the header design).

Things that I tried and figured out:
1). I know it has nothing to do with my css file made for the header, because I use that same file for all the other pages on my site that is not connected to the forum.

2). I know it has something to do with the headinclude section (located in the theme editing section), because I deleted the codes and scripts it had, and voila! My header looked perfect, but then, the rest of the forum was destroyed, hence I had to revert the code to default. I tried to cut certain codes out, but still no good results...

My Hypothesis:
There is a css file somewhere that controls the header text for the entire forum. From there I would be able to fix it (assuming I am correct). If I am correct, can someone tell where and what to look for?

Based on this information, is this enough for someone to help me out a bit? Just send me in the right direction, and I will be grateful. Thanks.