I don't know what to say about the gradient, maybe you should make it more like this?
Instead of just white, you could try mixing a yellowy color.
The rest is okay anyway, the BG and FG colors are fitting. I'd mess the sprites palettes as well, just like you did with the question blocks and everything there, since they stand out too much.
The design seems a tad linear, but I can't judge it properly just from screens.