Reading the instructions (), especially
"Your presentation should be something you're proud of. The user-experience and aesthetic aspects should be well considered."
I'd say they were looking for candidates who simply spend more time on the project. More CSS changes, more refactoring, maybe giving them a list of things you wish you had time to solve.
Entirely possible it's not code related at all. Them waiting for another candidate, somebody impressed them more for non-technical/coding reasons, hiring freeze the manager doesn't want to admit or internal discussions about the job role.
All you can do is send a nice email asking for feedback. If they don't provide that, move on.
) Took just 2 clicks to see the deleted files. It's possible to delete files from repositories including history.