artistsC01 width problem

I'm using version 5.x of artistsC01. I find that many of the users of my site are not able to view the right sidebar, a primary source of navigation, because their window size is small and the navigation therefore drops below the main page content. Is there a way to make the theme a fluid width so it adjusts to the users view? If not, can you tell me where the width and height areas are that I could try to manually adjust for users. I think people are just opening a browser and the window automatically opens to a certain size. Because it doesn't occur to them to maximize their window they can't find the navigation.

I just noticed in another persons earlier problem that artist.lupein has a way of making this a more liquid layout with a change to the CSS. I would very much appreciate having the details on how to do that and in what file.