The app has a black toolbar with white icons on it. When writing the
procedure I include the icon to the step, for example, "Tap Add [+]". The
white plus icon on black background looks strange, but that is how it looks
like in the interface. The black icon on the white/grey background looks
better, but it can confuse users. See attached. Should I leave it as is or
invert the icon? Is there any policy or best practice for this?