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[css3-ui] what to do if outline-offset is sufficiently negative (issue 38)

From: Florian Rivoal <florian@rivoal.net>
Date: Mon, 24 Nov 2014 17:53:18 +0100
Message-Id: <7BD827B7-D565-49BF-AB68-F480B8884D04@rivoal.net>
Cc: Tantek Çelik <tantek@cs.stanford.edu>, kennyluck@csail.mit.edu
To: www-style list <www-style@w3.org>
Raised here:
https://wiki.csswg.org/spec/css3-ui#issue38

about this:
http://dev.w3.org/csswg/css-ui/#outline-offset

The spec does not forbid negative values for outline-offset. In general this is fine, but if the negative value is large enough (in absolute value), the sides of the outline will meet in the middle of the box and pass each other, giving confusing and uninteroperable results.

Forbidding negative values entirely is probably not what we want, as small negative values are not problematic.

The most reasonable possibility suggested last time this was discussed would be for UAs to floor the at the largest (in absolute terms) value that doesn’t cause issues. Remains to define exactly where that is.

Possibilities:
a - at least 1px of the outline is still visible
b - the entire outline’s thickness is still visible
c - something else

Given that outline-style:auto can result in all sorts of shapes, including fuzzy ones where the last 1 px could be highly transparent, I’d favour b.

 - Florian
Received on Monday, 24 November 2014 16:53:45 UTC

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