RESOLVED INVALID 247862
Rendering bug when using position:fixed with containing block 
https://bugs.webkit.org/show_bug.cgi?id=247862
Summary Rendering bug when using position:fixed with containing block
webkit
Reported 2022-11-13 10:05:43 PST
For an example, see: https://game-point.net/misc/stickyMaskOverScroll/index4.htm When a div is created with 'position:fixed' inside a container div with 'transform:translate(0); overflow:auto; max-height:300px;', and it is then given a sibling div whose content causes the container to overflow, the 'fixed' div should not change its position when the overflowing content is scrolled, in the same way that it doesn't if the fixed positioning containing block is the viewport. However, when 'transform:translate(0)' is applied to the container to establish it as the fixed positioning containing block, the 'fixed' div starts to incorrectly become scrolled along with the overflowing content as if its positioning were set to 'absolute'. Relevant part of the CSS spec: https://w3c.github.io/csswg-drafts/css-position/#fixed-cb
Attachments
Add attachment proposed patch, testcase, etc.
Simon Fraser (smfr)
Comment 1 2022-11-14 11:08:49 PST
All browsers show similar behavior here, which I think is correct; if a position:fixed element has an ancestor with a transform,then the position:fixed should behave like position:absolute.
webkit
Comment 2 2022-11-14 15:50:34 PST
Agreed.
Note You need to log in before you can comment on or make changes to this bug.