Mobile-First Solution using CSS Flexbox & Media Queris

The Project was interesting to do as a beginner in web development lacking a lot of practice. it seemed simple but I do have doubts about it. that I hope some of you can clear for me.

The challenge was provided in mobile and desktop versions. I'm really doubting the way I used media queries I'm not sure I'm adhering to best practices on those and I feel like I'm not accounting for all possible screen sizes with the fear that some devices will have a messy layout.

I hope some of you will share how do they tackle this part of responsiveness of the challenge. Thank you!