Bug 113415 – margin-bottom ignored, causing simple page to render different than IE or Firefox

• Component: CSS
• Status: NEW

Created attachment 195336 [details]
Testcase

1) Run the attachmenet on Safari, Chrome, or nightly Webkit build.  
2) Shrink the browser window so there is a vertical scrollbar
3) Notice there is no margin-bottom like there is margin-top.
      -compare to Firefox and IE, both which allocate space for margin-bottom.

[Simon Fraser (smfr)]

This may be about margin collapsing. It's a margin on an element which is a child of an abspos div.

[Ahmad Saleem]

I am able to reproduce this bug using attached test case in Safari 15.6 on macOS 12.5 and if you scroll, you don't get "bottom" margin and it is also present in Chrome Canary 106 while Firefox Nightly 105 do show bottom-margin / white space below yellow block. I am going to mark this as "New". Thanks!

[Radar WebKit Bug Importer]

<rdar://problem/98331149>

[Ahmad Saleem]

This commit mentions about this Webkit bug:

https://src.chromium.org/viewvc/blink?view=revision&revision=164882

[Ahmad Saleem]

I test all attached tests from Blink's mentioned commit in Comment 04 and also attached but all of them are matching Chrome Canary 113 while Firefox Nightly 113 add "margin-bottom".

I am not sure on web-spec part but this is what the behavior is of Safari / WebKit in STP165.

@Alan - do we need to do behavior of "Firefox" or matching Chrome is fine?

Chrome Test in JSFiddle - https://jsfiddle.net/e48uyac6/show & https://jsfiddle.net/r5hbcLfu/show

[Ahmad Saleem]

(In reply to Ahmad Saleem from comment #4)
> This commit mentions about this Webkit bug:
> 
> https://src.chromium.org/viewvc/blink?view=revision&revision=164882

NOTE - this has bug where RenderBox.cpp changes were reverted in following commit:

https://chromium.googlesource.com/chromium/src.git/+/8f19da697b269b531791101e30a3ef1974c335b4