Chall using Flex, Grid, Javascript and some responsives

Hello guys, I'm back ! There is my second chall to learn Javascript, the accordion menu is very useful and cool to practice ! Yes, yes... my responsive for the left part is dégueulasse sa mère, I didn't succeed, especially on the box. I think I coded on a mistake (I should put an height in % or min/max), because my container is too big for the page in 375px and when I change this, everything breaks. (logic) And, how I could hide the image corner without hide the box? (I would use "overflow: hidden; but the box was hide)