User-Agent: Mozilla/5.0 (Windows NT 5.2; WOW64; rv:2.2a1pre) Gecko/20110402 Firefox/4.2a1pre Build Identifier: I presume that the ancient behaviour was okay. See following test: Reproducible: Always
http://www.w3.org/TR/css3-2d-transforms/#introduction says: Any value other than ‘none’ for the transform results in the creation of both a stacking context and a containing block. so the behavior you see is correct as far as I can tell.
Er, wrong resolution.
Okay, the behavior of Presto is similar, but Gecko 1.9.x et Webkit are a behavior different. It is strange to see like that with floating ojects.
Oups, sorry, it's only with Webkit.
I think that creating a stacking context is not enough for z-index to apply. For example, z-index does not apply to an element with opacity:0.5 but position:static.
OK. Note that Opera, IE9, and we all apply z-index to transformed content (presumably because the spec says it needs to act like position:relative). I guess we should see where the discussion on www-style ends up.