Bug 272339 - css zoom doesn't zoom font-size with -webkit-text-size-adjust: none
Summary: css zoom doesn't zoom font-size with -webkit-text-size-adjust: none
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: Safari 17
Hardware: iPhone / iPad iOS 17
: P2 Normal
Assignee: Nobody
URL: https://mikelehen.github.io/public-we...
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2024-04-08 10:25 PDT by Michael Lehenabuer
Modified: 2024-04-15 10:31 PDT (History)
6 users (show)

See Also:

Attachments
HTML test case demonstrating bug (773 bytes, text/html)
2024-04-08 10:25 PDT, Michael Lehenabuer 		no flags Details
Screenshot of issue (246.23 KB, image/png)
2024-04-08 10:25 PDT, Michael Lehenabuer 		no flags Details
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Description Michael Lehenabuer 2024-04-08 10:25:03 PDT 
Created attachment 470816 [details]
HTML test case demonstrating bug

See attached test case. Live repro here: https://mikelehen.github.io/public-web/tmp/safari-zoom.html

With -webkit-text-size-adjust: none; the CSS zoom setting seems to be disregarded when there's an explicit font-size within the zoomed element.

Notes:
1. Works in Chrome and Desktop Safari, but not iOS Safari.
2. The font sizes I'm using should be big enough to avoid minimum font sizes, and the bug repros with zoom <1 or >1.
Comment 1 Michael Lehenabuer 2024-04-08 10:25:31 PDT 
Created attachment 470817 [details]
Screenshot of issue
Comment 2 Simon Fraser (smfr) 2024-04-08 15:10:39 PDT 
Funny story about `-webkit-text-size-adjust`: it was added independently for macOS and iOS. On macOS it means just this: don't scale the font size with zoom. On iOS it means something different: don't apply font boosting logic. So we're kinda stuck with it.
Comment 3 Radar WebKit Bug Importer 2024-04-15 10:31:30 PDT 
<rdar://problem/126492290>