As mentioned in today's review, here, from Fantastic Four #256 (the first appearance of the new "Negative Zone" costumes), is what John Byrne was actually drawing:
And here's what he thought he was drawing:
And here's what every other artist thought he was drawing:
So despite Byrne's insistence, the costumes were never actually black, but they certainly weren't a vibrant Crayola color, either.
I think Jim Halpert did fine as Mr. Fantastic!
> Be the smartest man in the world
> Announce your strongest ally's major weakness to the villain
> Turn to look at the camera and frown comically