I've noted that the bbcode font sizing used in the editor (size 1-7) are actually hard coded in the source code - not even via a theme, it's actually in the php code itself (in 3 separate locations!).
Because we changed the base font used across our site to one which is slightly smaller than the default, we were forced to increased font sizes everywhere to compensate.
As a result, we have a situation where we have font size 4 smaller than font size 3 because 4 is hard-coded to 15px while size 3 is variable based on stylesheet settings.
I would have thought it would make more sense to use relative sizings for fonts? If size 4 is supposed to be "normal", then have size 3 as something like 90% of size 4 and size 5 as 110% ... or something along those lines. (Note also that currently in XenForo v1.4.7, size 3 is actually "normal", not size 4!!).
Either way, is there a technical reason why the font sizes (except "normal") are hard coded? Could this be made configurable by style/CSS adjustments?
The way things are now, the only real choice we have for setting the font size in the "messageSignature" style property is to something larger than 10px (size 2) and smaller than 15px (size 4), because we can't easily adjust the definition of the other font sizes.