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Re: [css3-values] viewport units (vw/vh/vmin/vmax) and @page rules

From: Simon Sapin <simon.sapin@kozea.fr>
Date: Mon, 12 Nov 2012 01:44:46 +0100
Message-ID: <50A0467E.4060901@kozea.fr>
To: www-style@w3.org
Le 11/11/2012 22:14, L. David Baron a écrit :
> (While I'm here, shouldn't the first quote above also mention that
> it's the first page?)

This is a separate issue. I’m starting another thread to avoid confusion.


> So, if we have:
>
>    @page {
>      margin-left: 10vw;
>    }
>
> should:
>    (1) the user-agent try to solve the relevant equations to find a
>    valid size for the page box given the margins?  (This seems like
>    it might be doable in a few of the simple cases, but certainly
>    isn't solvable in general.)
>
>    (2) the declaration be ignored?
>
>    (3) the declaration be treated as some other particular value
>    (e.g., '0', 'auto')?
>
> With css3-page, this problem becomes worse as the presence of the
> 'size' property defined in
> http://dev.w3.org/csswg/css3-page/Overview.html#page-size-prop
> means that we also have to describe how to handle either of:
>
>    @page { size: 50vw 50vh; }
>    @page { size: 50vh 50vw; }
>
> which I think means that option (1) isn't realistic.


Yes, this is basically a cycle in the definitions. As noted last month, 
it is also possible to construct a cycle involving `font-size` on the 
root element:

http://lists.w3.org/Archives/Public/www-style/2012Oct/0398.html

I agree with not doing (1). I prefer (2) (disallow some 
unit/property/context combination), but I could be convinced for (3) 
(only when a cycle is detected, some properties get their initial value 
to break the cycle.)

-- 
Simon Sapin
Received on Monday, 12 November 2012 00:45:25 GMT

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