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Re: [css3-values] Which font to use for the ex unit?

From: Gérard Talbot <www-style@gtalbot.org>
Date: Thu, 17 Jan 2013 14:38:02 -0500
Message-ID: <ac5073989200ea3cbaec6f0360ea4dd5.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Simon Sapin" <simon.sapin@kozea.fr>
Cc: "CSS WWW Style (www-style@w3.org)" <www-style@w3.org>

Le Jeu 17 janvier 2013 9:43, Simon Sapin a écrit :
> Hi,
>
> css3-values defines the ex unit as "Equal to the font's x-height." (and
> then goes into details of what the x-height is)

CSS 3 Values and Units, section 5.1.1. Font-relative lengths: the ‘em’,
‘ex’, ‘ch’, ‘rem’ units
http://www.w3.org/TR/css3-values/#ex-unit


> but does not say which
> font to use. This can be ambiguous eg. when font-family contains
> multiple valid family names.


Related test in CSS 2.1 test suite:
http://test.csswg.org/suites/css2.1/latest/html4/numbers-units-019.htm

Another (somewhat) related test in CSS 2.1 test suite:
http://test.csswg.org/suites/css2.1/nightly-unstable/html4/font-size-124.htm


CSS 2.1, section 4.3.2 Lengths states

"
ex: the 'x-height' of the relevant font
(...)
The 'ex' unit is defined by the element's first available font. The
exception is when 'ex' occurs in the value of the 'font-size' property, in
which case it refers to the 'ex' of the parent element.
"
http://www.w3.org/TR/CSS21/syndata.html#length-units

This chunk of text is most likely what is missing in
CSS 3 Values and Units, section 5.1.1. Font-relative lengths: the ‘em’,
‘ex’, ‘ch’, ‘rem’ units
http://www.w3.org/TR/css3-values/#ex-unit


Gérard
-- 
CSS 2.1 Test suite RC6, March 23rd 2011
http://test.csswg.org/suites/css2.1/20110323/html4/toc.html

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Received on Thursday, 17 January 2013 19:38:38 GMT

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