One minor improvemnet is that we’ve created a separate set of shadows for dark color palettes that are more opaque. So while a light color palette may have a shadow with a 0.15 opacity, a dark color palette will use 0.5 so it’s a little more apparent. This isn’t very helpful for color palettes with a pure black background though.
Another improvement worth looking into is something you can see on Github… in their dark color palette they make the dropdown backgrounds slightly lighter to give them more contrast from the background.
@cvx astutely pointed out that this is similar to what Apple suggests in their interface guidelines:
When two light interfaces are layered, a simple, diffuse drop shadow is all you need to create visual separation between the two. With dark interfaces, drop shadows are slightly less effective.
System background colors will use the darker or base values for background apps or interfaces and the lighter, elevated values for apps or interfaces that are in the foreground.
The concept is that since the dropdown is closer to the imaginary light source that casts the shadow, it should be brighter.