Changing the width of Content and Sidebar

Hi , I can only try to imagine the effect of the earthquakes on the life in Nepal now. My thoughts are with you, and I wanted to let you know that there is a substantial, organized effort, here in Vancouver, Canada, to help out. I hope it makes a difference. I will totally understand if you can't find the time to respond to all the questions, these days. I think mine may be a short one, and if you can reply, that would be very much appreciated. I recently bought the Adventurous Pro, and I would like to make the content area wider, and the right sidebar narrower. The new sidebar width should be about 200px ( Right now it's showing as 360 px , at full screen, for comparison ). The content area would be made wider , adding the width that the sidebar was shrunk. Is there an easy CSS fix for this ?