acquia marina theme

Have you tried organizing your blocks within the different regions? I just created a site using this theme and if you look at http://drupal.org/node/357261 you can see that by placing your blocks in one of the side bar blocks and the content blocks your content will then create different layouts (there are 4 available in total) if you don't like any of these 4 then you can customize such as customizing the right side bar (because it actually looks different than then the left - no borders, here is the link for that too in case you need it - http://drupal.org/node/315971). What I did was I copied the entire Style.css sheet into the local.css sheet and customized my CSS inside the local.css so that I then left my style.css alone incase I need to go back and copy it back in case something didn't work. Also I used the Developer toolbar in firefox (CSS/View Style information) to hover over regions on my website to check where I needed to alter my css - made editing my CSS super quick! Hope that helps and I am not repeating what you might already know but just wanted to try and help if I could.