Could someone please explain to me how the projects that place objects outside of projects work. I'm so confused. If anyone replies that would be awesome!

Me realizing that I have like 0 posts because I could never figure out how to get here. ) *sob*

There used to be a bug in the way that Scratch loaded vector costumes that allowed teporarily injecting custom CSS into the page while the costume was being loaded. The projects had two injecting costumes, the first one injected CSS that changed the appearance of the page, but normally this would change back when Scratch finishes loading the costume, so the projects also had a second injecting costume that started extremely long transitions from the changed page to the default

Thank you… So much