I made a test page concerning them and found a small inconsistency. Mozilla 5.0 Gecko use 16 px font-size:medium: according that xx-small should be 9px (in CSS2 the recommended scaling factor 1.2) BUT the main problem is still, that MS IE 5.0 font-size:medium ) 17px. If also Mozilla could use this value, all relative font-sizes from xx-small to large are exactly as big in both browsers. I made a bug report to Microsoft and complained about the inconisitency of relative font sizes in MS IE 5.0. In fact MS IE 5.0 works much more inconsistent, because undefined is too small and x-large and xx-large use inconsistent scaling factor (Mozilla 5.0 Gecko use consistent). Because MS IE don't have consistent relative font sizes, fonts are never exactly the same, but if they are same from xx-small to large, it could help much web page designers. Then they could easily make pages to work well in various browsers.

Changed to style system

The reporter contacted us by email and his comments have been added to bug 18136 "Fixing the font size mess". Closing as dup. *** This bug has been marked as a duplicate of 18136 ***

Marking verified dup of 18136.