Bug 492364

Summary:	CSS :is pseudo-class appears to be ignored by Falkon
Product:	[Applications] Falkon	Reporter:	rupert.levene
Component:	general	Assignee:	Unassigned bugs mailing-list <unassigned-bugs>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	jurajoravec
Priority:	NOR
Version:	3.2.0
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	demo html file firefox and falkon rendering

Description rupert.levene 2024-08-29 12:47:48 UTC

Created attachment 173087 [details]
demo html file

SUMMARY

The CSS :is pseudo-class appears to be ignored by Falkon.

STEPS TO REPRODUCE
1. Go to https://developer.mozilla.org/en-US/docs/Web/CSS/:is and look at the CSS Demo. Or load the attached file.

OBSERVED RESULT

The list renders as entirely blue in Falkon. 

EXPECTED RESULT

The list renders in blue, green and orange, like it does in Firefox.

SOFTWARE/OS VERSIONS
Ubuntu 22.04
Falkon application version 3.2.0, Ubuntu package version 3.2.0+dfsg1-1
QtWebEngine version 5.15.3

Comment 1 rupert.levene 2024-08-29 12:52:54 UTC

Created attachment 173088 [details]
firefox and falkon rendering

Comment 2 Juraj 2024-08-29 14:19:15 UTC

According to the "Browser Compatibility" table from the provided link[1], this feature was added to Chromium (Chrome) 88.
The QtWebEngine version provided in this bug report (5.15.3), it uses Chromium 87 as a backend.

So it is not implemented there, because it is too old.

Works perfectly fine on newer Falkon with Qt6 backend.

PS: You can check the Chromium version used for given QtWebEngine version at Qt wiki[2].

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/:is
[2] https://wiki.qt.io/QtWebEngine/ChromiumVersions