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z-index-abspos-009 invalid

From: L. David Baron <dbaron@dbaron.org>
Date: Sun, 17 Oct 2010 16:33:37 -0700
To: public-css-testsuite@w3.org
Cc: fantasai@inkedblade.net
Message-ID: <20101017233337.GA30869@pickering.dbaron.org>
I believe these tests:
http://test.csswg.org/suites/css2.1/20101001/html4/z-index-abspos-009.htm
http://test.csswg.org/suites/css2.1/20101001/xhtml1/z-index-abspos-009.xht
are invalid because the root element establishes a stacking context.
This is stated explicitly in 9.9.1 ("The root element forms the root
stacking context.").  It also seems clear from appendix E (although
I'm not sure why items (1) and (2) in the top level list are
separate.

Since the root element establishes a stacking context, none of its
descendants can paint underneath its border or background.  This
test asserts that the div with z-index: -1 (red border) paints
underneath the root element's border (green).  However, nothing can
paint underneath the root element's border except for the root
element's background.

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Sunday, 17 October 2010 23:34:09 GMT

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