Ok, I finally found a solution. I updated my XML files, please go ahead and follow this tutorial that will fix fonts for good: http://ubuntuforums.org/showthread.php?t=208396 - Problem was in fontconfig. Now fonts in Firefox are going to look good.
-- firefox is not honoring /etc/fonts/local.conf settings https://launchpad.net/bugs/42955 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
