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RE: [css-writing-modes][CSS21] propagation of 'direction' from <body>

From: Greg Whitworth <gwhit@microsoft.com>
Date: Fri, 20 Feb 2015 03:15:22 +0000
To: fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <BN3PR0301MB0868344D21602FD15098BFE0A42A0@BN3PR0301MB0868.namprd03.prod.outlook.com>
> On 02/18/2015 06:29 AM, Simon Pieters wrote:
> >
> >>    a) Propagating at the HTML layer removes all of the CSS complexities,
> >>       making it easier to fix all the bugs and keep them fixed. Only one
> >>       lookup needs to happen.
> >
> > Maybe it introduces other bugs instead?
> It's a much simpler operation, so while it might introduce other bugs, it has
> less potential for bugginess now and in the future.
> For example, besides the things tested (overflow, scrolling) printing is also
> affected by the root writing mode. It affects the direction of pagination, it
> affects which page is printed first (:left or :right), it affects whether :left is
> equivalent to :recto or :verso, etc. It also affects the cascade: whether
> margin-left maps to margin-start depends on the writing mode.
> Basically there are many, many interactions in CSS that would have to be
> special-cased, whereas at the HTML layer, it's merely a weird exception that
> <html> copies its 'dir' value from <body>.
> >>    b) Content that misplaces dir=rtl is handled, and improved because now
> >>       the <head> is also RTL.
> >
> > This is not relevant outside test cases.
> It affects <title> and its presentation. (Or should.)
> >> Wrt compat concerns of only handling dir=rtl and not 'direction: rtl':
> >>
> >>    Greg Whitworth found on a database of 1.3 million pages only 0.03% use
> >>    'direction: rtl' at all. The number setting that on <body> is a subset
> >>    of all that, and the number setting it on <body> and not <html> and
> >>    relying on that making the root behave as RTL is a subset of *that*.
> >
> > Did that database include external stylesheets?
> I don't know.

Yes, it includes everything that is fetched by a browser (JS/CSS/HTML, etc).
Received on Friday, 20 February 2015 03:15:55 UTC

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