Bug 160886 – Incorrect clipping of fixed elements inside element with opacity, position, mix-blend-mode or filter

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: CSS

Created attachment 286127 [details]
actual rendering

opacity, position, mix-blend-mode, filter should only create a new stacking context for its fixed descendants, and not create a containing block. Instead, in Safari this gets created, causing cropping of the fixed descendants
http://jsbin.com/coxoye/2/edit?html,output

[Simon Fraser (smfr)]

This is a compositing bug.

Created attachment 311507 [details]
Picture of the bug on chrome(left, how it should look like) and on safari (right, with bug)

I was having this bug too. Tested on iOS 10.3 (safari, iPad).

Link to demo: https://codepen.io/sofiapoh/pen/xdozJL

[L. David Baron]

Per the spec, *filter* should create a containing block for fixed-pos descendants; see my comment at https://bugs.chromium.org/p/chromium/issues/detail?id=797493#c6 .

That said, based on my test at https://dbaron.org/css/test/2018/stacking-context-z-order WebKit isn't creating a containing block for fixed descendants for any of these properties (perhaps comment 1 was indicating that comment 0's statement is too general?).

[Brent Fulgham]

We don't see an issue with this test case. If you believe there is still an issue, could you please REOPEN this bug with a small test case illustrating the issue?