With Bug 1794628, we will shortly implement the inverted-colors media query, part of Media Queries Level 5, behind a pref (layout.css.inverted-colors.enabled). Emulation for this query should also likely be added.

I would be curious what approach was taken with this. I'm implementation this feature in Chromium and I'm not sure if just triggering (inverted-colors: inverted) to match would be useful.

As then developers would see an otherwise not inverted page with all the media inverted?

See also: https://bugs.webkit.org/show_bug.cgi?id=259418