UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support Updated to 7.6 - Need CSS Help

Thanks to the help here I have fixed both the forum alignment issue and have updated to the 7.6 styles.

Now that I have it fixed, a related question on the forum width. Can I put something in the html includes or a CSS file to limit the forum width so it doesn't extend the full width? Kind of like the way this forum is with the grey sidebars outside the islands.