Back in the day, when I first got into super-hero comics, there was no consistency in how Batman and Superman put together their wardrobe--and it drove me crazy.
Batman's cowl was maybe separate or maybe joined to his cape or maybe both were joined to his costume. Superman maybe wore a separate top, or maybe he wore a blue onesie with the red trunks over that, or maybe the leggings were sewn to the trunks. Did Superman's leggings have feet or did they stop at the ankles? And if they stopped at the ankles, why didn't they ride up when he was in action.
It's amazing that some people assume that Superman is wearing a pair of trunks over a body suit--because there was never any evidence that was the case. Since the super-suit was often shown hanging on its own, it seemed like the whole thing was joined together. But then Superman would sometimes take off his cape or his boots or his shirt. And how exactly did he attach his cape to his shirt?
Well, the Captain Action Superman costume made it clear that the top was sewn onto the trunks and the trunks were sewn onto the leggings.