Yes, this fixed the problem for me. I'm using Fedora 5 and Firefox 22.214.171.124, and was experiencing exactly the same problem with the left margin, but, as far as I can tell, this fixed it.
There still seems to be an underlying issue with the left margin, however. When I enlarge the text using Firefox (Ctrl+) two times, the left margin problem returns. This didn't happen with formal_white under Moodle 1.5+.
But this is still a good fix. Thanks very much ATW!