Six Forgotten Warriors Chapter 5: The Price of Heroism - S5-E6
Plot hole: This series is in the same continuity as the other Marvel animated series from around the same time - X-Men, The Incredible Hulk, Iron Man, and Fantastic Four - by virtue of each aforementioned show crossing over with at least one of the others. This episode, which originally aired on October 17, 1997, establishes that Captain America had spent the last 50 years locked in another dimension with Red Skull, and the episode ends with he and Red Skull once again becoming trapped in the aforementioned dimension. However, the final episode of Fantastic Four, entitled "Doomsday," which originally aired on February 24, 1996, features a cameo by Captain America in the present day, attempting to stop a rampaging Dr. Doom.
Answer: I believe it was just a way to try and show the suit is "oily" or reflective. It also helps define the character's features since otherwise, he'd just be a flat black color. It's similar to how the black suit Spidey had blue outlines. (I don't know why they chose a pink/red color... maybe because red is associated with power/fire/war, so it's a more "evil" color?)
TedStixon