How to do a responsive page?

Question

Hii. I'm trying to do a CSS Art for a Front-End challenge that was organized by DEV Community ( if you're interested, here is the link for the event: https://dev.to/challenges/frontend-2025-10-15 ). My idea is to do shelves with different potions. For now, I'm doing and draft about the potions, and I'm struggling with doing ''responsive''. Sorry if my code is messy.
Btw, if you have any suggestions about my code or have errors that I need to improve would be helpful.
https://www.sololearn.com/compiler-playground/WV329mBwFty5/?ref=app

Answer 1

I didn't see flexbox. maybe you should read about that

Answer 2

flexbox or grid.