The current css based layouts are broken on Mozilla/Firefox. Columns are glued to the left instead of being arranged side by side. Imho css layouts are generally still very buggy.
I switched back (again) to table based layouts and noticed some side effects regarding font sizes in IE and some problems with the customizer. I believe some of the recent changes (esp. with the 2.0 final release) to the portal layout have not been adapted to the tcolumns/layout.vm.
So I wrote a new table based layout.vm and used the actual css based layout.vm as a master. I just inserted two or three tables and removed the css width attributes.
This now works as expected and exactly looks like the css based layout.
I'd like to see the attached patch to be applied. Please read a comment in the patch about a workaround to handle .99% widths.