Another option could be to restrict the dark pseudo to all color related fields, but allow EVERY combination that the developer might see fit, e.g. different border widths in dark mode like @StrangeTech proposed, in another context.
That concept would follow the feature request I put up the other day:
With a text input for classes in place we could just write dark:rounded-md for example.
This allows for a workflow that is far less error prone, yet offers endless possibilities for combining Tailwind pseudo-classes.