Remove 'no-preference' from prefers-color-scheme @media feature

Category: CSS
Type: New or changed feature
Status: Enabled by default (Chrome 80)
Intent stage: Evaluate readiness to ship

Breaking change: No
Enterprise impact: None
Spec maturity: Working draft
Web Platform Tests: Yes

WPT details: Test changes already landed: https://chromium-review.googlesource.com/c/chromium/src/+/2232924

Summary

The prefers-color-scheme feature in Media Queries Level 5 supported three values: 'no-preference', 'light', 'dark'. Remove the support for the 'no-preference' value because it has been removed from the specification.

Motivation

The value has been removed from the spec. We did not report 'no-preference' for any OS.

Standards & signals

Specification: https://drafts.csswg.org/mediaqueries-5/#prefers-color-scheme
Firefox: Positive — Firefox want to remove this as well. See link.
Safari: Positive — I have asked on webkit-dev@, but there is previous statement from Apple from a discussion a year ago: "hober: We have no notion of no-preference on our platforms. At OS install time, we prompt the user to pick light or dark. You have to to move on to the next screen. There is no system concept of no preference. We're not interested in pretending otherwise." See: https://github.com/w3c/csswg-drafts/issues/3857#issuecomment-499261339
Web developers: No signals
Tracking bug: https://bugs.chromium.org/p/chromium/issues/detail?id=1091806

Ecosystem

Web Platform Tests: https://wpt.fyi/results/?q=remove-no-preference-from-prefers-color-scheme-media-feature
Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+Remove%20'no-preference'%20from%20prefers-color-scheme%20%40media%20feature
MDN Web Docs: https://developer.mozilla.org/en-US/search?q=Remove%20'no-preference'%20from%20prefers-color-scheme%20%40media%20feature
Baseline status: https://webstatus.dev/?q=Remove%20'no-preference'%20from%20prefers-color-scheme%20%40media%20feature

View on chromestatus.com