The postwar period was known as "The Atomic Age". Harvey's JOE PALOOKA #15 featured a character called "Atoma", a pretty girl in a futuristic costume that enabled her to fly. Art by the Bob Powell studio. Originally published in 1947.
Superheroes rarely teamed up in the old comics. But THE HUMAN TORCH #33 had a story where the Torch and Sun Girl ( his sidekick in that period ) teamed up with Captain America, even if the Captain's actual involvement in the story was brief. Art by Mike Sekowsky.