I’m not that far into the projects, but I like it. Hovering over the buttons work and the function of the actual calculator works.
Personally, I dislike the type papyrus, but that is me. However, I do notice if I change the font-family to something else it breaks the alignment everything – maybe something to resolve, as when the font cascades to helvetica it messes up, but works with times new roman.
Also green on blue doesn’t look good to me. Maybe a nice brown for the background, or another warm color like dark orange. All my opinion of course.