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Re: [css-values] Line-height relative length units 'lh' and 'rlh'

From: MURAKAMI Shinyu <murakami@antenna.co.jp>
Date: Wed, 04 Jun 2014 03:56:51 +0900
To: Gérard Talbot <www-style@gtalbot.org>
Cc: www-style@w3.org
Message-Id: <20140604035651.8E95.C598BCD7@antenna.co.jp>
Gérard Talbot <www-style@gtalbot.org> wrote on 2014/06/02 5:25:35
> Le 2014-06-01 03:29, MURAKAMI Shinyu a écrit :
> > I would like to propose new relative length units:
> >     'lh'    line-height of the element
> >     'rlh'   line-height of the root element
> > (refer the used value of the line-height property)
> > The line-height relative length units are necessary for specifying
> > the block-size of a block container using number of lines.
...

> I think your proposal is impractical, not suitable; lh as an unit would be referring to a length that is not, for practical purposes, predictable. Not all line boxes have the same height.
> 
> line-height as a property defines the minimum height of line box; line-height does not define an height but a minimum rather:
> 
> "
> 'line-height' specifies the minimal height of line boxes within the element. The minimum height consists of a minimum height above the baseline and a minimum depth below it
> "
> http://www.w3.org/TR/CSS21/visudet.html#propdef-line-height
> 
> and so the actual line box height could be greater.

Yes, I know the CSS2's line box model.
The page '@page { height: 20rlh }' cannot always have 20 lines,
but defining the area size based on the line-height setting 
makes sense to me.  I don't expect the exact number of lines 
in this case.

Thanks for the detailed explanation of the CSS line-height model :)


Shinyu Murakami
Antenna House
Received on Tuesday, 3 June 2014 18:57:18 UTC

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