I am using the twenty eleven theme (eprawnik24.com/)

I would like to set the auto resolution on the site regardless of the user's monitor settings. Resolution which I would use is 1366 x 768 Is there a way to do it? I read some instructions, but they were not too helpful.

I figured that I need to change some lines in style.css, but which ones?
pastebin.com/fAzQ0eAd

As you can see, in 1366 x 768 my site looks like this:
postimg.org/image/w41uxaxr1/

In another resolution sideareas and floating objects begin to collide. I hope someone will be able to advise me how to set the auto resolution for all users.