Moz has a similar bug in their bugzilla https://bugzilla.mozilla.org/show_bug.cgi?id=243519
Created attachment 8757 [details] test case in Strict mode
Created attachment 8758 [details] test case in Quirks mode
This is a stunning change from CSS2. I do not believe it is compatible with the existing Web either. We should think very carefully before fixing this.
Created attachment 11109 [details] Patch that fixes the containing block for positioned elements to be the RenderView ("initial containing block" in CSS terms) Here we go. A followup improvement I can make after this goes in is to eliminate the RenderLayer for the root element.
Disregard my dramatic comment. I didn't quite understand the 2.0 -> 2.1 spec change. I do now, and it's not that scary. :)
Comment on attachment 11109 [details] Patch that fixes the containing block for positioned elements to be the RenderView ("initial containing block" in CSS terms) r=me
Fixed.
(In reply to comment #7) > Fixed. Tests in r17067, fix in r17068.