Glossary

Forced-colors mode

An operating-system high-contrast setting that overrides author colours with a system palette. CSS exposes it via @media (forced-colors: active) and the system-colour keywords CanvasText, ButtonFace, Highlight.

Windows High Contrast and the GNOME high-contrast theme both map to forced-colors: active in CSS. About 4% of Windows users have forced-colors enabled at any given time. Authors should respect the system colours rather than fight them: use CanvasText for text, ButtonFace for button backgrounds, Highlight for selected state. forced-color-adjust: none opts a small region out, useful for brand logos.