Responsive four card layout using flex box

What are you most proud of, and what would you do differently next time?

Mastering flexbox, but struggling with spacing, padding and positioning. I would like to get better in these aspects as well.

What challenges did you encounter, and how did you overcome them?

Didn't know how to adjust 4 cards first, but took some help online to see how to achieve it using flexbox.

What specific areas of your project would you like help with?

I would appreciate any feedback on the overall responsiveness and suggestions to improve.