Bug 250831

Summary: REGRESSION (254010@main): text-decoration-thickness style not being applied to underlines under <a> tags with embedded <ruby> tags
Product: WebKit Reporter: Chris Vasselli <clindsay>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: mmaxfield, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 16   
Hardware: All   
OS: iOS 16   
See Also: https://bugs.webkit.org/show_bug.cgi?id=244623
https://bugs.webkit.org/show_bug.cgi?id=257992
https://bugs.webkit.org/show_bug.cgi?id=264245
Attachments:
Description Flags
Xcode project illustrating the issue
none
Testcase as HTML none

Description Chris Vasselli 2023-01-19 03:53:56 PST
Created attachment 464555 [details]
Xcode project illustrating the issue

As of Safari 16.2 the text-decoration-thickness style no longer seem to affect the underlines of links that contain embedded <ruby> tags. This behavior seems new as of either Safari 16.1 or 16.2.

Steps to Reproduce:
I have attached an Xcode project that reproduces the issue in a simple iOS app. 

1. Open the Xcode project and run it against an iOS 16.2 simulator. This will simply open the file index.html in a WKWebView.
2. Note that the first link (with an embedded ruby in it) appears offset by 20px and in red, showing that the text-underline-offset and text-decoration-color properties are being applied correctly.
3. Note that the first link has the default thickness, showing that the text-decoration-thickness property is not being applied correctly.
4. Note that the second link (without embedded ruby) appears with a thicker underline, showing that the text-decoration-thickness property is being applied.

Now, rerun the Xcode project against an iOS 16.0 simulator. Note that the first link now matches the appearance of the second link, and the text-decoration-thickness property is applied correctly.

Expected Result:
I would expect the underline under the first link to appear as thick as the second link.

Using Xcode Version 14.2 (14C18).

Also reproducible in Safari on Mac: Version 16.2 (18614.3.7.1.5)
Comment 1 Radar WebKit Bug Importer 2023-01-19 19:17:34 PST
<rdar://problem/104457938>
Comment 2 zalan 2023-01-19 19:43:39 PST
Works: 254008@main
Fails: 254011@main

254010@main is a strong candidate (Stop inheriting text-decoration-thickness CSS property)
Comment 3 Tim Nguyen (:ntim) 2023-03-09 13:48:36 PST
Created attachment 465380 [details]
Testcase as HTML