Glad you enjoyed playing!
The shop bug is known a classic case of checking full inventory before checking if you are buying / selling XD
We definitely want to see proper indicators of all stats everywhere, not just in the shop & battle, just crunch happened. For now we have a wiki , but Its mainly a crutch.
Thanks for the feedback on the UI and interactions I agree 100% we should look into those!
Black screen is a when hitting back & forward is a general itch issue I have had happen on other games too, pretty sure its for having "start game when page loads" enabled, but as our game is rather small we want to enable it for a better general UX, will try figure out if we can check blank screens to force a refresh though...
Definitely a big thank you for the feedback & playing :D