A PostCSS plugin to use relative chroma in an upgraded oklch() CSS notation. Check the live demo to see it in action.
The proposal is:
oklch(gamut L RC H)
gamut can either be srgb, display-p3 or p3 (same), and rec2020.
Exemple: oklch(p3 80% 100% 20) which means: "for a lightness of 80 % and a hue of 20, I want a color with the maximum chroma possible in the P3 gamut" and translates to oklch(80% 0.148 20).
This is a work in progress that might change in the future.
There is a discussion in csswg-drafts repo.
The plugin has not yet been published on NPM. To use it, you can download the dist folder and configure your postcss.config.js file to use it.
Check the demo repo to see how I use it.