I've skimmed through these docs, and personally it seems like an unnecessary feature.
The explainer says a considered alternative is "font-size: medium would always be affected by the OS-level font scale." with cons "Sites are NOT built correctly and things that used to just look small would now be clipped You can simulate the effect of this alternative in Chrome by setting the UA-level font at chrome://settings/fonts. Set "font-size" to the maximum. old.reddit.com, gmail, etc, all break. Sites today ineffectively mix px and em because there is no safeguard against doing so — few authors change the UA-level font-size at chrome://settings/fonts." So why would introducing another way to adapt to the user's preferred font size fix the root problem? Developers will continue to create bad code with pem instead of em which break when the user sets a higher font size. You mention that "Currently, it is not practical for a page to detect if the user has changed their preferred font size via the Operating System's preferences." That's not always true, for example on Chrome OS the system wide font size setting (also used for Android apps) has been Chrome's web font size settings. But my biggest concern is backwards compatibility. Does this work mean that em/rem will no longer scale with font size settings in the future? On Thu, May 22, 2025 at 10:07 PM Domenic Denicola <dome...@chromium.org> wrote: > > > On Fri, May 23, 2025 at 9:00 AM Chromestatus < > ad...@cr-status.appspotmail.com> wrote: > >> Contact emails dgro...@chromium.org, p...@chromium.org >> >> Explainer https://davidsgrogan.github.io/env-explainer.html >> >> Specification https://drafts.csswg.org/css-env-1/#text-zoom >> >> Summary >> >> Exposes a user's preferred font scale to CSS. Currently, it is not >> practical for a page to detect if the user has changed their preferred font >> size via the Operating System's preferences. This CSS environment variable >> will reflect the scale chosen by the user. >> >> >> Blink component Blink>Accessibility >> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EAccessibility%22> >> >> TAG review https://github.com/w3ctag/design-reviews/issues/1101 >> >> TAG review status Pending >> >> Risks >> >> >> Interoperability and Compatibility >> >> None >> >> >> *Gecko*: No signal ( >> https://github.com/mozilla/standards-positions/issues/1229) >> >> *WebKit*: No signal ( >> https://github.com/WebKit/standards-positions/issues/499) >> >> *Web developers*: Positive ( >> https://github.com/w3c/csswg-drafts/issues/10674) This proposal started >> with a request from a BBC developer >> >> *Other signals*: >> >> WebView application risks >> >> Does this intent deprecate or change behavior of existing APIs, such that >> it has potentially high risk for Android WebView-based applications? >> >> None >> >> >> Debuggability >> >> This can be debugged using existing devtools support by connecting to a >> device. We have a plan for making this easier at >> https://crbug.com/419595584. >> >> >> Will this feature be supported on all six Blink platforms (Windows, Mac, >> Linux, ChromeOS, Android, and Android WebView)? No >> >> Initial support will be limited to Android, which has limited practical >> ability to respect the OS font scale today. On Windows, we scale the entire >> browser in response to the OS setting, and some followup work is needed to >> support this while not double-zooming. >> > > I'd like to learn more about this from a compat and interop perspective. > From skimming the explainer, this seems like a complicated problem space. > > If we never ship support on desktop, and authors start using this feature, > what will the user experience be? > > If we don't ship support on desktop for 10 milestones, but then suddenly > do, what will the user experience be? > > You mentioned Windows, but what about macOS, Linux, ChromeOS, and Android > WebView? > > >> >> >> Is this feature fully tested by web-platform-tests >> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >> ? Yes >> >> This is tested with internal WPT tests due to lack of support for OS font >> scale setting in tests. >> https://github.com/web-platform-tests/wpt/issues/12725 >> >> >> Flag name on about://flags None >> >> Finch feature name CSSPreferredTextScale >> >> Rollout plan Will ship enabled for all users >> >> Requires code in //chrome? False >> >> Tracking bug https://crbug.com/397737223 >> >> Measurement UseCounter: >> https://chromestatus.com/metrics/feature/popularity#CSSEnvironmentVariable_PreferredTextScale >> >> Estimated milestones >> Shipping on Android 138 >> >> Anticipated spec changes >> >> Open questions about a feature may be a source of future web compat or >> interop issues. Please list open issues (e.g. links to known github issues >> in the project for the feature specification) whose resolution may >> introduce web compat/interop risk (e.g., changing to naming or structure of >> the API in a non-backward-compatible way). >> https://github.com/w3c/csswg-drafts/issues/10674 >> >> Link to entry on the Chrome Platform Status >> https://chromestatus.com/feature/5328467685801984?gate=6195643460354048 >> >> Links to previous Intent discussions Intent to Prototype: >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOZbSt1dSWUwuFD%2Bu%3DwGXf-ubdgh8K%3D0oj13%3DkrvADSOM41xtw%40mail.gmail.com >> >> >> This intent message was generated by Chrome Platform Status >> <https://chromestatus.com>. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to blink-dev+unsubscr...@chromium.org. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/682fba7d.170a0220.2aa17e.152d.GAE%40google.com >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/682fba7d.170a0220.2aa17e.152d.GAE%40google.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9kLUA-FJ_et-2%3DbVCVJ6miD6zNw1LgJYNTAh8fiE_8WA%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9kLUA-FJ_et-2%3DbVCVJ6miD6zNw1LgJYNTAh8fiE_8WA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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