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[csswg-drafts] [css2][css-sizing][css-tables] Percentages used to compute to auto, now compute to a percentage but are used as auto

From: François REMY via GitHub <sysbot+gh@w3.org>
Date: Tue, 21 Feb 2017 21:55:28 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-209284820-1487714127-sysbot+gh@w3.org>
FremyCompany has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [css2][css-sizing][css-tables] Percentages used to compute to auto,
 now compute to a percentage but are used as auto ==
It seems the group accepted an 
[errata](http://www.w3.org/Style/css2-updates/REC-CSS2-20110607-errata.html#s.10.5a)
 in 2013 regarding the computed value of the "height" property. I 
think that was a mistake and would like to revert that errata. It was 
applied in those 
[two](https://github.com/w3c/csswg-drafts/commit/b66760ec149cec9c26d60ccb4ee6347d17bb4e9c)
 
[commits](https://github.com/w3c/csswg-drafts/commit/b61e2a26b218da47cde50a762443f9344bc9737a).

This change requires to complexify all other specs in order to deal 
with the case of "broken percentages" everywhere we want to deal with 
the "auto" case. Since most specs didn't this is bound to continue to 
cause issues when developers reimplement specs or part of specs, like 
what happened in [this Chrome 
issue](https://bugs.chromium.org/p/chromium/issues/detail?id=687551#c17).

Other specs continue to assume the old behavior, like css-sizing (in 
multiple places). Furthermore, it specifies this behavior for other 
values like fill-content etc when they can't resolve, like we do for 
percentages. 

> Note that percentages resolved against the intrinsic sizes 
(max-content, min-content, fit-content) will compute to auto, as 
defined by CSS 2.1. 

> [...] if the computed inline-size of the block is fit-content, auto,
 or stretch, its min-content inline-size contribution is its 
min-content inline size plus any inline-axis margin, border, and 
padding. 

> It is appropriate to resolve percentage heights on direct children 
of table cells if the cell is considered to have its height specified 
explicitly or the element is absolutely positioned, see CSS 2. It is 
further clarified that a cell is considered to have its height 
specified explicitly if the computed height of the cell [...] is a 
length or percentage.

cc @tabatkins @fantasai @dbaron @SimonSapin @bert-github 

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/1051 using your GitHub 
account
Received on Tuesday, 21 February 2017 21:55:35 UTC

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