jeff salty at 8:16AM, July 15, 2021

The red borders is something that pro artist Alex Toth did. It helps tell you where to stop your lines while you're inking in black, so you don't accidentally run out of the panel. The red became black on copies of the original art, which was then colored. That would have been true had I published it back in 1981, but NOW it's easier just to leave them red.