Model8c.html

Preferences: Arial 16.
CSS: *, body, td {font-family:Arial,sans-serif;}.
Arial 16px - xx-small - small - medium - undefined.
Browsers:
NN = Netscape Navigator
IE = Microsoft Internet Explorer
Op = Opera

Below is the result in Windows browsers with preferences above (values are in pixels and the aqua background color shows the calculated value according to CSS2).

Browser: Font size:	NN 4.04	NN 6.2.1	IE 5.5	*IE 6.0 ()**	Op 3.62	Op 5.0	Op 6.0	*Op 7.0 Beta1 ()**
xx-small	8	9	10	9	9	15	13	13
x-small	11	10	13	10	11	18	18	13
small	13	13	16	13	13	22	22	18
medium	16	16	19	16	16	25	24	22
large	25	18	23	18	19	32	32	24
x-large	36	23	32	23	23	45	44	32
xx-large	54	32	48	32	28	64	64	43

Opera 3.62 - works exactly according to CSS2 (indeed the relative scaling factor can be changed). Medium is the same as the undefined font size, and in the German version it matches to the default font size (I some English Opera 3.6x the default font size matched to the font-size small).
Netscape 6.x and MS IE 6.0 (in the standard-compliant mode, why I have used in the table above the '*' mark) - quite consistent behavior except the largest value (one evaluation version of Netscape worked as well as Opera 3.62). Medium is the same as the undefined font size. It also matches to the default font size of browsers.
MS IE 5.x and MS IE 6.0 (not in the standard-complian mode) - partially inconsistent behavior. From xx-small to large goes according to CSS2 recommendation, but x-large and xx-large has 1.5 as the scaling factor. Medium is one step bigger font size than the default font size, which is the same as small. Also Opera 4.x works approximately at the same way.
Opera 5.x+ and Netscape 4.x - very inconsistent behavior.
- Opera 5.x-6.x relative font size difference varies between 1.1-1.5 (a little bit depending on the used version). The font size medium doesn't correspond with the default (undefined) font size. the undefined font size from the preferences with the setting 16 pixel is something between xx-small and x-small. If the default font size is defined as 12 pixel, Opera works apporiximately at the same way as MS IE 5.x. In other settings font sizes are totally different.
- Opera 7.0 Beta1. Opera has a some kind of DTD-switch, where in "standard mode" (that's why I have used in the table above the '*' mark) the text size is smaller, but the browser works always very inconsintent.
- Netscape 4.x use normally according to CSS1 the relative font size difference 1.5, but between x-small to medium is used 1.2. Undefined font size depends on default settings. Changing the default font size doesn't affect to relative font sizes defined with CSS.

NoteThe most odd matter is between Opera 3.62 and Opera 5.0. Opera Software knows, how relative font sizes should be handled. But because MS IE works inconsistent, it doesn't know, what to follow - MS IE or the specification. Because the behaviour of MS IE 6.0 for Windows is DTD-dependent (CSS Enhancements in Internet Explorer 6 Public Preview), also Opera would need a DTD-switch.

I got an e-mail from MAC-user. Macintosh G3 PowerPC / MacOS 8.0 use smaller font sizes.

Browser: Font size:	NN 4.7	MS IE 4.5	MS IE 5.0
xx-small	6	9	10
x-small	8	10	13
small	10	12	16
medium	12	14	16
large	18	18	24
x-large	28	24	32
xx-large	40	36	48

Neither Mac browsers work consistent. MS IE 4.5 for Mac follows approximately the same calculation principles between font sizes as MS IE 5.x for Windows, but a little bit an-exactly. If font small is 12px, the series of MS IE 4.5 for Mac should be in my mind: 8, 10, 12, 14, 17, 26, 38/39. DTD has no effect in this matter for MS IE 5.0 for Mac. Netscape 6.x for Mac behaves presumably at the same way as corresponding Windows versions. Then Netscape 6.x is the only browser in Mac, which behaves quite consistent.