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Re: [CSS21] CR-CSS21-20070719, 8.3.1 Collapsing in presence of min/max-height, small correction suggested

From: Arron Eicholz <Arron.Eicholz@microsoft.com>
Date: Mon, 21 Jul 2008 13:53:32 -0700
To: "www-style@w3.org" <www-style@w3.org>
Message-ID: <66D5CB5D6AB0694592FAF5487C50368B21236A01B6@NA-EXMSG-C111.redmond.corp.microsoft.com>

> In 8.3.1:
>
> "The bottom margin of an in-flow block-level element with a 'height' of
> 'auto' and 'min-height' less than the element's used height and 'max-height'
> greater than the element's used height is adjoining to its last in-flow
> block-level child's bottom margin..."
>
> I suggest the following small corrections:
> - "less than" should be "less than or equal" (or "not greater than")
> - "greater than" should be "greater than or equal" (or "not less than")
>
> This would be more consistent with the rules at 10.7 and more logical:
> roughly speaking when min-height is exactly equal to the element's used
> height, then min-height is not really in effect, and all should be as in the
> case of min-height less than the element's used height.
>
> Firefox is the only browser that I know that stops that margins collapsing
> when min/max-height is in effect, and it behaves according to the suggested
> change.

Fantasai and Arron wrote some tests for this issue:
  http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0048/no-min-height.htm
  http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0048/min-gt-height.htm
  http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0048/min-eq-height.htm
  http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0049/max-eq-height.htm
  http://lists.w3.org/Archives/Public/www-archive/2008Jul/att-0049/max-lt-height.htm
from which we conclude that
  - Safari and Opera do not disable margin collapsing when min-height or
    max-height is in effect.
  - IE never collapses
  - Firefox collapses when min-height or max-height is equal to the height,
    *eats* the inner margins both when max-height is in effect /and/ when
    min-height is in effect. We would expect that disabling margin-collapsing
    when min-height is effect would cause the margins to add, not the inner
    margin to be truncated.
and therefore this entire paragraph should be removed from the spec.

--
Fantasai and Arron Eicholz
Received on Monday, 21 July 2008 20:54:13 GMT

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