Bug 160886

Summary:

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

Product:

WebKit

Reporter:

valdrinkoshi

Component:

CSS

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED CONFIGURATION CHANGED

Severity:

Normal

CC:

bfulgham, dbaron, simon.fraser, sofia.pohjalainen, zalan

Priority:

Version:

Safari 9

Hardware:

Mac

OS:

OS X 10.10

See Also:

https://bugs.webkit.org/show_bug.cgi?id=160953

Attachments:

Description	Flags
actual rendering	none
Picture of the bug on chrome(left, how it should look like) and on safari (right, with bug)	none

Description valdrinkoshi 2016-08-15 18:04:39 PDT

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

Comment 1 Simon Fraser (smfr) 2016-08-17 22:02:44 PDT

This is a compositing bug.

Comment 2 sofia.pohjalainen 2017-05-30 08:43:11 PDT

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

Comment 3 sofia.pohjalainen 2017-05-30 08:45:50 PDT

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

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

Comment 4 L. David Baron 2018-05-31 21:26:03 PDT

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?).

Comment 5 Brent Fulgham 2022-07-14 16:35:21 PDT

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?