Chris MillsI've finally managed to get relative CSS colors documentation published on MDN. This was a complex beast to tackle, and I'm proud to see it out! Get started at https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_colors/Relative_colors; also see the color function pages to find out what relative colors look like in each.
Using relative colors - CSS | MDN
The CSS colors module defines relative color syntax, which allows a CSS <color> value to be defined relative to another color. This is a powerful feature that enables easy creation of complements to existing colors — such as lighter, darker, saturated, semi-transparent, or inverted variants — enabling more effective color palette creation.
Daryl Zuniga