258886 2023-07-05 08:41:08 -0700 offsetParent is wrong for a nested element 2025-12-25 15:42:05 -0800 1 1 1 Unclassified WebKit DOM WebKit Nightly Build Mac (Apple Silicon) macOS 13 RESOLVED CONFIGURATION CHANGED https://bugs.webkit.org/show_bug.cgi?id=19923 https://bugs.webkit.org/show_bug.cgi?id=253147 https://jsfiddle.net/xjsm5489/show InRadar P2 Normal --- 1 i.am.kanaru.sato webkit-unassigned ahmad.saleem792 mike simon.fraser webkit-bug-importer zalan oldest_to_newest 1965124 0 466934 i.am.kanaru.sato 2023-07-05 08:41:08 -0700 Created attachment 466934 this html produces the bug Hi, hope you all are well :) I found offsetParent is wrong for a bit nested element. In the attached HTML, the offsetParent of the div element with id, "target", should be the span with id, "offsetParent". But the webkit(265767@main) recognizes the offsetParent is the span with id, "not-offsetParent". It affects many libraries which insert elements with consideration of setting position properties correctly. This kind of library, e.g. floating UI, detects offsetParents of elements and calculates the position related properties of element to be inserted. (floating UI: https://github.com/floating-ui/floating-ui) FYI: I found the offsetParent is correctly set when you remove the parent element(div) of the element with id, "target". But idk this helps debug. Thank you for checking this report and look forward to your reply :) 1965129 1 i.am.kanaru.sato 2023-07-05 08:44:32 -0700 I've already checked chrome and firefox correctly recognize the offsetParent...! 1965168 2 ahmad.saleem792 2023-07-05 11:28:20 -0700 I am able to reproduce this bug on WebKit ToT (265772@main) and Safari 16.5.1, so it might not be recent regression. 1965214 3 zalan 2023-07-05 15:38:30 -0700 This is caused by the continuation tree structure (caused by the inline level element's block level child <span><div>) where we fail to follow the continuation chain for our containing block. 1965218 4 ahmad.saleem792 2023-07-05 16:31:38 -0700 (In reply to zalan from comment #3) > This is caused by the continuation tree structure (caused by the inline > level element's block level child <span><div>) where we fail to follow the > continuation chain for our containing block. By any chance, is this relevant WPT? http://wpt.live/css/cssom-view/offsetParent-block-in-inline.html 1965250 5 zalan 2023-07-05 20:01:05 -0700 yeah(In reply to Ahmad Saleem from comment #4) > (In reply to zalan from comment #3) > > This is caused by the continuation tree structure (caused by the inline > > level element's block level child <span><div>) where we fail to follow the > > continuation chain for our containing block. > > By any chance, is this relevant WPT? > > http://wpt.live/css/cssom-view/offsetParent-block-in-inline.html yah, it's all about continuation. :/ 1965874 6 i.am.kanaru.sato 2023-07-09 22:03:44 -0700 Thank you for giving replies :) I'd like to debug and fix it. Could I try that? According to your guess, I will take a look on the below parts of WebKit. - `RenderObject::offsetParent()` - `RenderElement::canContainAbsolutelyPositionedObjects()` BTW, should I refer to the below page for how to debug webkit? https://webkit.org/debugging-webkit/ Actually, I'd tried to build and run webkit on local before according to this link, and didn't succeed...TT If there was the better or latest document, could you please give me that?? 1966391 7 webkit-bug-importer 2023-07-12 08:42:17 -0700 <rdar://problem/112140677> 1968747 8 ahmad.saleem792 2023-07-29 06:30:54 -0700 (In reply to Kanaru Sato from comment #6) > Thank you for giving replies :) > > I'd like to debug and fix it. Could I try that? > According to your guess, I will take a look on the below parts of WebKit. > - `RenderObject::offsetParent()` > - `RenderElement::canContainAbsolutelyPositionedObjects()` > > BTW, should I refer to the below page for how to debug webkit? > https://webkit.org/debugging-webkit/ > Actually, I'd tried to build and run webkit on local before according to > this link, and didn't succeed...TT > > If there was the better or latest document, could you please give me that?? I think you can try bug 253147, which has more details in where the culprit code is and also potential Blink merge candidate. Also can you share your steps and what error you faced? Also join WebKit Slack Channel to get more help and support on how to build local WebKit test environment. 2161849 9 ahmad.saleem792 2025-11-28 11:09:32 -0800 Solved with `Block-in-inline` work. 2168202 10 ahmad.saleem792 2025-12-25 15:42:05 -0800 Resolved in Safari Technology Preview 234. 466934 2023-07-05 08:41:08 -0700 2023-07-05 08:41:08 -0700 this html produces the bug file_258886.txt text/plain 786 i.am.kanaru.sato PCFET0NUWVBFIGh0bWw+DQo8aHRtbCBsYW5nPSJlbiI+DQogIDxoZWFkPg0KICAgIDxtZXRhIGNo YXJzZXQ9IlVURi04IiAvPg0KICAgIDxtZXRhIG5hbWU9InZpZXdwb3J0IiBjb250ZW50PSJ3aWR0 aD1kZXZpY2Utd2lkdGgsIGluaXRpYWwtc2NhbGU9MS4wIiAvPg0KICAgIDxtZXRhIGh0dHAtZXF1 aXY9IlgtVUEtQ29tcGF0aWJsZSIgY29udGVudD0iaWU9ZWRnZSIgLz4NCiAgICA8dGl0bGU+U3Rh dGljIFRlbXBsYXRlPC90aXRsZT4NCiAgPC9oZWFkPg0KDQogIDxib2R5Pg0KICAgIDxkaXYgaWQ9 J25vdC1vZmZzZXRQYXJlbnQnIHN0eWxlPSJwb3NpdGlvbjogYWJzb2x1dGU7Ij4NCiAgICAgIDxz cGFuIGlkPSdvZmZzZXRQYXJlbnQnIHN0eWxlPSJwb3NpdGlvbjogcmVsYXRpdmU7IHRvcDogMTAw cHg7IGxlZnQ6MTAwcHg7Ij4NCiAgICAgICAgPGRpdj4NCiAgICAgICAgICA8ZGl2IGlkPSJ0YXJn ZXQiIHN0eWxlPSJwb3NpdGlvbjogYWJzb2x1dGU7IHRvcDoxMDBweDsgbGVmdDoxMDBweDsiIj4N CiAgICAgICAgICA8L2Rpdj4NCiAgICAgICAgPC9kaXY+DQogICAgICA8L3NwYW4+DQogICAgPC9k aXY+DQogIDwvYm9keT4NCiAgPHNjcmlwdD4NCiAgICBmdW5jdGlvbiBtYWluKCkgew0KICAgICAg Y29uc3QgdGFyZ2V0ID0gZG9jdW1lbnQuZ2V0RWxlbWVudEJ5SWQoJ3RhcmdldCcpDQogICAgICB0 YXJnZXQuaW5uZXJUZXh0ID0gYG9mZnNldFBhcmVudCBpcyAke3RhcmdldC5vZmZzZXRQYXJlbnQu aWR9YA0KICAgIH0NCiAgICBtYWluKCkNCiAgPC9zY3JpcHQ+DQo8L2h0bWw+