Hi Joe,
Actually, you have that file included. I'm sorry, I missed it.
The problem, I believe, is that the width in your .art-contentLayout .art-content selector in style.css is set to 499px. Set this to 755px. The style-artisteer-overrides.css file will set the width for the proper selectors when you use the left or right panes.
HTH,
Joe D.