While HA Client 0.4.0 is in work I want to share one of the latest features.
The new custom color picker for RGB lights. It is now more accurate. For most light bulbs the color in app will be the same as color of bulb itself. Also it is now plased right on the entity view instead of popup. Current light color is highlighted.
This is a HSV palette and the color for light entity is set now also in HSV fomat instead of RGB. HS to be exact, because V (the value) of color is always 100 for light entity.