Indexhibit Support

Hello,
Maybe someone could help me with this...
I'm using the columner theme and I'd like the menu horizontal "bar" to be centered (x axis) in the window browser (whatever it's length)
I did this with the PRE-NAV, using "position: static;" but cannot do it with the nav bar. It seems I can't find where I need to write the order (in the style.css, nothing happens, in the reset.css won't work either)
I'm not very versed in css, but maybe someone could help me to find the way?
Thank you!

P.S.: for clarification, I want the nav bar to behave the same as the pre nav is doing now (not necesarily together, but if it must be...)
I've also tried with 'position: fixed; width: 100%; left: 50%; right: -50%;' but with that I need to design for a specified size)
Thank you a lot, really.

the url is: fa000131.ferozo.com/

I found it!
In the #index, changed the width: 50%, and added

margin-right: auto;
margin-left: auto;
display: block;

So, for future reference:
If someone wants to center the menu horizontally, and the exhibit (I'm using the "over and over" format)

go to > style.css and add

1. margin-right: auto;
2. margin-left: auto;
3. display: block;
4. width: 50%;
5. in the #index and #exhibit

That did it for me.