#11530 resolved on accepting one or more colors in color-mix() but 11.1. Serializing color-mix() still defines how to serialize with exactly two colors.

More specifically, it defines when percentage values must be omitted. Or for example, when the specified value is color-mix(blue, 70% yellow), it wants color-mix(blue 30%, yellow), which is not shorther.

Should it be expanded? changed? dropped?