Browser window size – main content and side bar width

When the browers window is at 1200px, the main content is set at a width of 75% and the side bar at 25%. When the browser window is made smaller at a min-width of 992px, the body is 66.6% and side bar 33.3%.

Is there an easy way to change this to 75% / 25% as well? I found this code in the pinnacle.css file but there are many places where this has to be changed.

Thanks!