W3C home > Mailing lists > Public > www-style@w3.org > May 2009

Re: bolder/lighter defintion

From: Zack Weinberg <zweinberg@mozilla.com>
Date: Mon, 18 May 2009 11:06:06 -0700
To: Thomas Phinney <tphinney@cal.berkeley.edu>, W3C Emailing list for WWW Style <www-style@w3.org>
Message-ID: <20090518110606.232acc01@trurl>
Thomas Phinney <tphinney@cal.berkeley.edu> wrote:
> 
> But until somebody tells me differently, I am going to assume that one
> of the overarching principles of the spec is to try to make it so that
> following the spec well will generate compatible UA implementations.

I don't think this is wrong ...

> > The CSS font-weight property does not take arbitrary numeric values,
> > only "nice even 100s".
> 
> That would arguably be a bug in the CSS font-weight property spec,
> then.

... and I'm not saying the spec is correct as written, either.  I just
brought up the current wording of the spec to explain why John's
proposed new semantic for bolder/lighter is internally consistent.

> >  Mapping those to whatever's in the font file is presumably the
> > UA's problem.
> 
> Why? That seems like yet another way of ensuring that different UAs
> get different results with the same CSS+fonts.

My understanding is that CSS contemplates nine possible font weights,
which happen to be assigned the ordered sequence of labels 100,
200, ... 900.  These don't (as far as I know) line up neatly with the
weight properties in any font format, so there has to be some mapping
established by the UA.  There are guidelines for that mapping in the
spec, but it may not be possible to nail things down perfectly.

zw
Received on Monday, 18 May 2009 18:06:50 GMT

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