212372 2020-05-26 06:18:29 -0700 Element.offsetParent of fixed position element under transformed element should not be null 2025-09-19 17:22:01 -0700 1 1 1 Unclassified WebKit DOM Safari 13 All All RESOLVED FIXED https://bugs.webkit.org/show_bug.cgi?id=161788 InRadar P2 Normal --- 289743 1 federico.zivolo fantasai.bugs ahmad.saleem792 annevk ap bfulgham browserbugs2 davide.cavarretta fantasai.bugs mrobinson rniwa simon.fraser webkit-bug-importer zalan oldest_to_newest 1656012 0 federico.zivolo 2020-05-26 06:18:29 -0700 Reported by federico.zivolo@gmail.com in https://bugs.chromium.org/p/chromium/issues/detail?id=20574#c67. For the following test case: <!DOCTYPE html> <div id="transformed" style="transform: translateX(2px); height: 50px;"> <div id="fixed" style="position: fixed">FIXED</div> </div> <div id="output" style="height: 3000px"></div> <script> output.textContent = fixed.offsetParent ? fixed.offsetParent.id : "null"; </script> Chrome: null Firefox: transformed Firefox's behavior is more reasonable because "transformed" is the container of "fixed". This issue is somewhat related to https://bugs.webkit.org/show_bug.cgi?id=37839 1657104 1 webkit-bug-importer 2020-05-28 17:33:12 -0700 <rdar://problem/63739636> 1846631 2 browserbugs2 2022-02-28 07:21:49 -0800 " The offsetParent attribute must return the result of running these steps: If any of the following holds true return null and terminate this algorithm: (...) The element’s computed value of the position property is fixed. " https://www.w3.org/TR/cssom-view/#dom-htmlelement-offsetparent 1846828 3 simon.fraser 2022-02-28 15:55:11 -0800 (In reply to Gérard Talbot from comment #2) > " > The offsetParent attribute must return the result of running these steps: > > If any of the following holds true return null and terminate this > algorithm: > > (...) > > The element’s computed value of the position property is fixed. > " > > https://www.w3.org/TR/cssom-view/#dom-htmlelement-offsetparent But that probably hasn't been updated since we made certain CSS properties trigger containing block for fixed position (like transforms and filters). The real question here is whether the 'offsetParent' algorithm should follow containing blocks. Related: bug 161788 1887029 4 ahmad.saleem792 2022-07-27 03:51:24 -0700 I am still able to reproduce this in Safari 15.6 on macOS 12.5 using test case from Comment 0 changed into below JSFiddle: Link - https://jsfiddle.net/ewhjmx3a/show In case of Safari 15.6 and Chrome Canary 106, the output is "FIXED" & "null" on test case while for Firefox Nightly 104, it is "FIXED" & "transformed" aligned with Comment 0. I am not clear on web-spec but I think it should be something which needs to be clarified and all browsers should be on consensus. Just wanted to share updated results. Thanks! 2143479 5 fantasai.bugs 2025-09-16 17:19:49 -0700 This has been clarified in the spec at https://drafts.csswg.org/cssom-view/#dom-htmlelement-offsetparent 2143482 6 fantasai.bugs 2025-09-16 17:35:37 -0700 Pull request: https://github.com/WebKit/WebKit/pull/50834 2143689 7 ews-feeder 2025-09-17 12:03:45 -0700 Committed 300097@main (6cd7aec93667): <https://commits.webkit.org/300097@main> Reviewed commits have been landed. Closing PR #50834 and removing active labels. 2144561 8 ews-feeder 2025-09-19 17:22:01 -0700 Committed 297297.443@safari-7622-branch (ec961398d781): <https://commits.webkit.org/297297.443@safari-7622-branch> Reviewed commits have been landed. Closing PR #3673 and removing active labels.