I like your pixel style button and the graphics. Nice the sell and roll system as well. if you can make the instructor little text size and clear text type would be better but it is not necessary.
I also made one inventory system last semester. You can made this type very logic proved your code also very well. I like this turn page button and the grid layout. Very directly to the user. Comfortable user experience.
But i am not sure why I cannot listen the audio.
I like your game idle