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Re: [css3-transforms] Missing text about transforms inducing an abs-pos containing block

From: Øyvind Stenhaug <oyvinds@opera.com>
Date: Wed, 08 Aug 2012 12:15:36 +0200
To: www-style@w3.org
Message-ID: <op.wipv4aa5bunlto@oyvinds-desktop>
On Wed, 08 Aug 2012 10:56:40 +0200, Aryeh Gregor <ayg@aryeh.name> wrote:

> On Wed, Aug 8, 2012 at 2:11 AM, Robert O'Callahan <robert@ocallahan.org>  
> wrote:
>> The spec says "The object acts as a containing block for fixed  
>> positioned
>> descendants." It also needs to say that the object is a containing  
>> block for
>> abs-pos descendants too.
>
> I see
>
> """
> Any value other than ‘none’ for the transform results in the creation
> of both a stacking context and a containing block. The object acts as
> though position: relative has been specified, but also acts as a
> containing block for fixed positioned descendants.
> """
> http://dev.w3.org/csswg/css3-3d-transforms/
>
> This seems pretty clear to me.  Were you reading an outdated draft?
> As is generally the case at the W3C, we don't mark them clearly
> enough, so people sometimes get confused.

That ED is dated 28 January 2012, whereas  
http://dev.w3.org/csswg/css3-transforms/ is dated 27 July 2012.

The latter says

"In the HTML namespace, any value other than ‘none’ for the transform  
results in the creation of both a stacking context and a containing block.  
The object acts as a containing block for fixed positioned descendants."

and

"Any value other than ‘none’ for the transform results in the creation of  
both a stacking context and a containing block. The object acts as a  
containing block for fixed positioned descendants."

which is less clear (though "acts as though position: relative" was  
misleading too, and should not be reinstated).

Seems to me that it would be better to explicitly say how  
http://www.w3.org/TR/CSS21/visudet.html#containing-block-details is  
modified. A containing block is a rectangle, not a box or element or  
whatever the term "the object" is supposed to refer to.

-- 
Øyvind Stenhaug
Core Norway, Opera Software ASA
Received on Wednesday, 8 August 2012 10:16:09 GMT

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