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[css-writing-modes][CSS21] propagation of 'direction' from <body> (was Re: [CSSWG] Minutes Telecon 2014-07-09)

From: L. David Baron <dbaron@dbaron.org>
Date: Mon, 22 Sep 2014 13:39:32 -0700
To: www-style@w3.org
Message-ID: <20140922203932.GA667@crum.dbaron.org>
On Thursday 2014-07-10 11:28 -0400, Dael Jackson wrote:
> CSS Background Issue
> --------------------
[...]
>   SimonSapin: Do we only get writing mode direction from the root
>               element?
>   Rossen_: I think for IE we always propagate from body or HTML.
>   Rossen_: We treat it the same way to the root element which HTML
>            spec says that we take those and leave body so it has a
>            chance to redefine for overflow or writing. If HTML
>            doesn't have it we take it from body.
>   SimonSapin: The spec says don't do that.
>   Rossen_: Which?
>   <SimonSapin> http://dev.w3.org/csswg/css-writing-modes/#direction
>   SimonSapin: Link above
>   <SimonSapin> "Note that the direction property of the HTML BODY
>                element is not propagated to the viewport. That
>                special behavior only applies to the background and
>                overflow properties."
>   Rossen_: That spec was written 5 years after we did that
>            implementation. Maybe it now says something different,
>            but that's what we do.
>   Rossen_: It's interesting that it deviates from how we handle
>            overflow. I would expect the same.
>   fantasai: We had a legacy constraint that we were hoping wasn't
>             there for direction.
>   fantasai: We wanted authors to tag the root.
>   Rossen_: If you haven't implemented writing-mode, maybe. If you've
>            had it for a long time then you have an issue and if you
>            write ignoring that, you can avoid the issue.
>   fantasai: This is direction. It's been around since the 90's.
>   fantasai: Everyone's implemented it.
>   Rossen_: Right.
>   <plh> (fyi: the note was including in the FPWD of writing modes
>         back in 2010, but it's not part of CSS2.1)

For what it's worth, the WG explicitly resolved *not* to propagate
direction from <body> when resolving CSS 2.1 issues; see the
resolution to Issue 239 in
http://lists.w3.org/Archives/Public/www-style/2011Mar/0258.html .

I'd be ok with switching to match the background and overflow
propagation rules if there are sites out there that depend on it,
but if we do, we should make it an errata to CSS 2.1.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)

Received on Monday, 22 September 2014 20:39:58 UTC

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