Music was by Dan Ch. He made a soundtrack for the manga
before the anime came out, and I think it sounds beautiful, go check it out! :D https://www.youtube.com/watch?v=o51b7XkulCg&t=70s
I made the top background by borrowing images from user katelinelaine on devianart (Link: https://www.deviantart.com/katelinelaine)
and both the opening and ending of the anime's theme. The bottom image is from the ending of the anime. Finally, the folder's bunny image was obtained from the anime's wiki site: https://yakusokunoneverland.fandom.com/wiki/Little_Bunny
though I re-colored most of it when I downsized it.