how do i set my site width to 100% ?

i'm using red passion template.

when i put "width: 100%" under #mainWrapper in css, i don't get the result i want cause some tables (?) stay in wrong size.

what else do i have to change?

you can see the site on www.bali.hr (still working on it...)

BTW, is there an addon like the one i installed on www.bali.hr/shop for categories menu? i've used dynamenu for oscommerce and the one i used for this zencart is not like that one...

thanks!