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Re: [css21] line-height, problem?

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Mon, 26 Nov 2012 16:01:08 -0800
Message-ID: <CALRQH79wHyRb3z81EOyhheO5cV8Eeiqhk0jQVAEWpLbYKuumPQ@mail.gmail.com>
To: www-style@gtalbot.org
Cc: www-style@w3.org
Hmm, seems like my understanding of word "minimal" is completely wrong.

Consider this very simple doc:
https://dl.dropbox.com/u/14981836/line-height-test-min.htm

At the moment the spec[1] says:

"On a block container element whose content is composed of
inline-level elements,
'line-height' specifies the minimal height of line boxes within the element."

But UAs render this example as if 'line-height' specifies not the minimal height
but just height of line boxes.

Either spec is wrong with use of "minimal" there or UAs are wrong all together.

[1] http://www.w3.org/TR/CSS21/visudet.html#propdef-line-height

-- 
Andrew Fedoniouk.

http://terrainformatica.com

On Mon, Nov 26, 2012 at 11:18 AM, "Gérard Talbot" <www-style@gtalbot.org> wrote:
>
> Le Lun 26 novembre 2012 13:51, Andrew Fedoniouk a écrit :
>> On Mon, Nov 26, 2012 at 12:14 AM, L. David Baron <dbaron@dbaron.org>
>> wrote:
>>> On Sunday 2012-11-25 23:21 -0800, Andrew Fedoniouk wrote:
>>>> This sample:
>>>>
>>>> https://dl.dropbox.com/u/14981836/line-height-test.htm
>>>>
>>>> contains two identical paragraphs, the only difference is that
>>>> first one has line-height:normal and second one - line-height:1em;
>>>>
>>>> According to the spec [1]:
>>>>    'line-height' specifies the *minimal* height of line boxes within
>>>> the element.
>>>>
>> ...
>>>>
>>>> I suspect that I miss something between lines of the spec.
>>>> My understanding of the spec wording is this:
>>>>
>>>> used-line-height = max( {normal-line-height}, {defined-line-height} );
>>>>
>>>
>>> (1) when you're testing line-height, you should really test
>>> standards mode rather than quirks mode; quirks mode behavior is
>>> substantially different (and not fully explained by the first two
>>> items in http://quirks.spec.whatwg.org/#css ).
>>>
>>> (2) 'normal' and '1em' are *very* different in terms of how they
>>> inherit when the font size changes (since '1em' inherits as the
>>> computed value, which is no longer relative to the changed
>>> descendent font size).  'normal' and '1' are much more similar.
>>>
>>> -David
>>>
>>
>> Thanks, David. I've updated the sample with HTML5 doctype.
>> That actually makes no difference (only IE started to match
>> all other UAs here).
>>
>> In fact I've missed that part in the spec:
>> "On a non-replaced inline element, 'line-height' specifies the height
>> that is used in the calculation of the line box height."
>
> Right here, the "calculation of the line box height" should be a link to
>
> http://www.w3.org/TR/CSS21/visudet.html#line-height
>
> And the sentence itself is not easy to figure out. It should be saying
> instead/rather:
>
> "On a non-replaced inline element, 'line-height' specifies its height
> which will be used in the calculation of the line box height."
>
> because
>
> "
> The height of each inline-level box in the line box is calculated. For
> replaced elements, inline-block elements, and inline-table elements, this
> is the height of their margin box; for inline boxes, this is their
> 'line-height'.
> "
> http://www.w3.org/TR/CSS21/visudet.html#line-height
>
>>
>> So for such elements (like <big> in my sample) line-height defines
>> not "min-line-height" but just 'line-height' allowing to reduce it.
>> Together with the fact that line-height is an inheritable property
>> that creates such strange effect.
>
> Not sure what you're trying to say... but I definitely agree with you that
> this part of the spec - without useful diagrams and judicious explaining
> schemas - is difficult to visualize, to conceptualize.
>
> Gérard
> --
> CSS 2.1 Test suite RC6, March 23rd 2011
> http://test.csswg.org/suites/css2.1/20110323/html4/toc.html
>
> Contributions to CSS 2.1 test suite
> http://www.gtalbot.org/BrowserBugsSection/css21testsuite/
>
> Web authors' contributions to CSS 2.1 test suite
> http://www.gtalbot.org/BrowserBugsSection/css21testsuite/web-authors-contributions-css21-testsuite.html
>
Received on Tuesday, 27 November 2012 00:01:35 GMT

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