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Re: [css3-page][css3-multicol] margins at page or column breaks

From: MURAKAMI Shinyu <murakami@antenna.co.jp>
Date: Sun, 11 Jan 2009 16:07:07 +0900
To: robert@ocallahan.org
Cc: "Hakon Wium Lie" <howcome@opera.com>, www-style@w3.org
Message-Id: <20090111141641.A0AA.C598BCD7@antenna.co.jp>

"Robert O'Callahan" <robert@ocallahan.org> wrote on 2009/01/10 4:15:35
> On Sat, Jan 10, 2009 at 6:17 AM, MURAKAMI Shinyu <murakami@antenna.co.jp>wrote:
> 
> >
> > Probably it should be changed to:
> >    The top margin of the first element and the bottom margin of the
> >    last element in the multi-column element will be set to zero.
> >
> 
> This doesn't work well when you have content that may be rendered by
> browsers that don't support columns. In those browsers, those margins won't
> just disappear, they will collapse to form space above and below the
> multi-column element (asuming the multi-column element doesn't have border
> or padding). So it's more consistent with the non-columns case to allow
> margins to collapse through the boundaries of the multi-column element.

So the spec should be like the following?

    The top margin of the first element and the bottom margin of the
    last element will be set to zero if the multi-column element has
    border or padding, otherwise will collapse with the margins of the 
    multi-column element.

This seems not easy to understand though.

I thought that the multi-column element should establish  a new
formatting context ("flow root" in css3-box[1]), like table-cells, and
vertical margins of such elements do not collapse with its in-flow
children.
This model may have problem but I think the problem about browsers that
don't support columns have to be taken care by stylesheets authors.

[1] http://www.w3.org/TR/css3-box/#flow-root

-- 
Shinyu Murakami
http://www.antennahouse.com
Antenna House Formatter
http://www.antenna.co.jp/AHF/en/
Received on Sunday, 11 January 2009 07:07:52 GMT

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