At its simplest, this outfit is just blouse, a skirt, and a hair clip, but for some reason Millie makes it look like something much more complex. Imagine this picture but with a huge title saying "YOUNG LEIA: A STAR WARS MOVIE." It would fit perfectly, right? I don't know if that's Millie, the outfit, or both. All I know is that one day the fans will demand that Millie play young Leia.
Stranger Things Fact Number Thirty Five: There are flashback scenes in season two that are, spoiler, heartbreaking. They show Hopper's life when his daughter was still alive. Because those scenes take place much earlier, Hopper's hair is CGI. You really have to come to terms with your baldness when people need to see CGI your hair. That's not a permanent solution to hair loss, dude.