Reacting to the used `color-scheme` property with the `light-dark()` CSS function

[czerkies]

• https://drafts.csswg.org/css-color-5/#light-dark

This function computes to the computed value of the first color, if the used color scheme is light or unknown, or to the computed value of the second color, if the used color scheme is dark.

light-dark(<color>, <color>);