Re: [csswg-drafts] [css-color-adjust-1] Specification can define non-author color adjustment behavior more clearly (#13460)

Absolutely, so my understanding with browser extensions is as follows (maybe this is bit of a reach) BUT

Spec explicitly notes that forced-colors, system colors, and getComputedStyle() expose user preferences and can increase fingerprinting surface. BUT the spec says this for only user prefs; you can extend it to non-author interventions

For example: 
Dark Reader (and similar OSS extensions) watches OS/theme state and then applies a consistent, cross-site restyling.
Because that restyling often touches color-scheme / system colors / forced-colors-related behavior, any site (including 3rd-party iframes) can often detect “an extension is intervening” by observing computed styles and palette outcomes.

https://github.com/darkreader/darkreader/blob/0706f4b800c12891d133f291aea36d696f4c9187/src/inject/color-scheme-watcher.ts#L42-L44 
The referenced file does not inject styles itself; it detects system theme changes and notifies the extension, which then performs the styling elsewhere, but you get the point. 

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Received on Tuesday, 17 February 2026 23:11:30 UTC