Re: CSS 2 font-size clarification.

Mikko Rantalainen wrote:

Thanks for replying.

> Richard York / 2004-07-23 11:15:
> 
>> I have a question concerning the use of absolute size keywords for the 
>> font-size property.
>> [...]
>> To get down to my questions.. in CSS 2.1 and 3 apparently a new 
>> scaling factor was necessary, however, there appears to be no 
>> suggested starting point (or example) as there was in CSS 2, with the 
>> language:
>>
>> "if the 'medium' font is 12pt"
>>
>> Though vague as it was it appeared that UAs used it, which resulted in 
>> consistent behavior, whether intentionally or not. (at least as far as 
>> Windows UAs are concerned, I haven't yet tested on other OSs).
>>
>> What was the reason for the elimination of this language? Secondly 
>> since   in this case there appears to be a consistent behavior between 
>> UAs, why was the spec changed at all? Why not just add more keywords 
>> to preserve BC with the existing implementations?
> 
> Do you still believe that web pages are meant to look *identical*?

No, I guess not. I did quite a bit of research on this and I guess it 
comes down to these font sizes are supposed to be based on the user's/UA 
's font size preferences. So the medium size changes based on that 
preference. That wasn't immediately obvious from the spec. But in light 
of that these keywords make much more sense to me.

> Why is having some predefined 'medium' font size bad? Because I, you  or 
> the spec writer cannot know the *correct* size for the *end user*. For 
> example, the 'pt' unit is short for point. And one point is 1/72th of an 
> inch or 0.353 mm. Think about a text with 12pt font size projected to 10 
> foot screen; kind of small, isn't it? (Notice that I mean 12 point text, 
> not something that current UAs render as "12pt" because the display's 
> pixels per inch (or DPI) measure is incorrect or unknown. On the other 
> hand, if your vision was below average it might be that you couldn't 
> read anything below 36pt (absolute unit!) no matter how near you could 
> get to the text. It would really suck to have browser that had 12pt 
> 'medium' font size just because the spec said so, wouldn't it? ...well, 
> you get the point (pun intended =) ...

haha! Well, my test case was somwhat misleading [1]. I already 
understood the caveats with absolute units, and seeing that language in 
the spec only led to more confusion, since when I set up test cases side 
by side it appeared the UAs were using the point sizes mentioned there 
and Mozilla 1.8 and Opera 7.5 both adjust point sizes with changes in 
the user's font size preferences, therefore the size remained consistent 
with resolution changes and changes to the font size preferences. As for 
the DPI, it seems that most browsers force 96 dpi to remain consistent 
with Win IE. Even Safari does this. Is this assertion correct? Most UA's 
have standardized de facto on 96 DPI?

> As for the 12pt that browser manufacturers default to? It's just the 
> size that Netscape 3.x (or earlier version?) defaulted and every browser 
> has used the same default ever since because "otherwise the page would 
> look different". Most people with average vision would rather read 11pt 
> or 10pt text but *you as an author should NOT readjust the font size* 
> just because *you* think that the user hasn't corrected the default, yet!

The problem is HTML legacy! I've gotten very used to wanting a pixel 
perfect reproduction of my page for all UAs that often times I simply do 
not account for font size variations.. yes, bad practice I know, it 
takes time to leave behind the legacy imprint of presentational markup 
and train yourself to think in terms of liquid design.

>> Forgive my ignorance.. I'm trying to present the material for a book, 
>> so I need a good understanding of what led to the change and what 
>> effects, 
> 
> At least you're doing research for your book ;-)

Thanks for entertaining my questions. Of course I think the most 
important thing about writing a book is presenting the information as 
accurately as possible! Lest anyone with a clue about the technology 
think me a complete idiot ;-).

[1] http://www.smilingsouls.net/CSS/font-size/font-size-all.html

Regards,
Richard York

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Received on Sunday, 25 July 2004 22:29:14 UTC