Yeah, that black line is normal. The Overworld fills up much of that space, and textboxes go down there too. Usually, ZSNES allows one line of black underneath every photo (even if its a pic of the OW).
Radical Dreamers is perhaps easier to see because it's two times bigger on screen and the entire monitor is black. Taking screenshots has frustrated me, so in some cases in the encyclopedia, I'm pairing normal shots with ones that have been gamma corrected.