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[RC6] Several background-0* tests inaccurate

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Sat, 24 Mar 2012 14:42:14 -0400
Message-ID: <9f3f845a33eb29bcda48b3aa9c3f3ee1.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Public CSS test suite mailing list" <public-css-testsuite@w3.org>
Hello,

Several background-* tests create another form of fractional pixel. They
try to position a background-image at the middle (centered vertically)
of an element which is 1px taller than the image. So browsers have to
decide where such extra pixel is going to go: at the top or at the
bottom... because such pixel can not be splitted.

This is what is happening in many tests: the cat image (serving as
background-image) is 99px tall while the containing element is 100px
tall.

E.g.:

[RC6]
http://test.csswg.org/suites/css2.1/20110323/html4/background-035.htm

[nightly-unstable]
http://test.csswg.org/suites/css2.1/nightly-unstable/html4/background-035.htm

Opera 11.61 will show a tiny horizontal black line below the right foot
of the cat.

Firefox 11.0 and Chrome 17.0.963.83 will show such same tiny horizontal
black line above and close to the right ear of the cat.

This by itself does not prevent making a reftest; the requirement for
making a reftest is not achievable to begin with.

I do not see the need to update the test right now but I am reporting
this as an inaccuracy which could have been avoided by setting the
wrapping div height to 99px instead of 100px.

Gérard
-- 
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CSS 2.1 Test suite RC6, March 23rd 2011:
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Received on Saturday, 24 March 2012 18:42:46 GMT

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