Color value accepted in style serialization: Compose Color, hex, or rgba(...) string.
rgba(...)
Compose color; serializes via toRGBAString.
Hex token (#RRGGBB or #AARRGGBB); passed through as-is.
#RRGGBB
#AARRGGBB
CSS-style rgba(r,g,b,a) string; passed through as-is.
rgba(r,g,b,a)
Mapbox-style rgba(r,g,b,a) string (hex/RGBA variants returned unchanged).