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Re: [css21] computed value of top/bottom for relative positioning

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 16 Jun 2010 11:00:27 -0700
Message-ID: <4C19113B.6050005@inkedblade.net>
To: Anne van Kesteren <annevk@opera.com>
CC: "L. David Baron" <dbaron@dbaron.org>, www-style@w3.org
On 02/12/2009 02:48 PM, Anne van Kesteren wrote:
>
> On Thu, 12 Feb 2009 22:06:46 +0100, L. David Baron <dbaron@dbaron.org>
> wrote:
>> On Thursday 2009-02-12 19:51 +0100, Anne van Kesteren wrote:
>>> http://www.w3.org/TR/CSS21/visuren.html#position-props states that for a
>>> relative positionined element the computed value of 'bottom' (which is
>>> also the inherited value) is defined in
>>
>> I think we probably want the "Otherwise:" text from the computed
>> value line to apply to the non-auto relative positioning case.
>
> Yes.
>
>
>> However, I wonder if all of these adjustments (except for what's in
>> the "Otherwise:" text) should be adjustments to the used value
>> rather than the computed value, so that they don't affect
>> inheritance. I'm willing to guess that might be more consistent
>> with implementations. (Do you have testcases?)
>
> E.g.
>
> <!doctype html>
> <style>
> div { border-top:1px solid }
> #a { margin-top:30px; height:100px }
> #b { position:relative; bottom:10%; height:100px }
> #c { position:relative; top:inherit }
> </style>
> <p>Should there be three thin lines below or one thick and one thin?</p>
> <div id=a><div id=b><div id=c></div></div></div>
>
> ... does seem to confirm that.
>
> If you change top to bottom you do get three lines. If you give top the
> supposed computed value of top on #b (-10%) you also get three lines. If
> you remove height on #b and change top to bottom you get a different
> result in Opera and Firefox because Opera resolves percentages to lengths.

Proposed changes to specify this behavior, if this is what we want:

   In 9.3.2 remove "for 'position:relative', see section Relative Positioning."
   for top, right, left, and bottom.

   In 9.4.3 change 4 instances of "computed" to "used".

~fantasai
Received on Wednesday, 16 June 2010 18:01:16 GMT

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