(The discussion started under the heading "font-family font sizes", but I
now changed the Subject to more specific.)
On Fri, 18 May 2007, Bruno Fassino wrote:
Putting together the above, if we trust Gecko, the aspect ratio of a
font can be obtained simply observing the size of an element
dimensioned using 'ex' units.
The results are consistent with those I got with my simplistic method that
compares the letter x in large font size with a stickyard. See
http://www.cs.tut.fi/~jkorpela/x-height.html
It seems that different ways lead to the same results, implying that the
figures mentioned in CSS specifications are wrong - most notably when
they say that Verdana has an aspect ratio of 0.58, but it actually has 0.545.
This, as well as methods of finding out the x-height value for specific
fonts, is of some importance to authors who wish to use font-size-adjust
(which helps on Firefox 2 and does no harm when it doesn't).