Responsive Card Design Using CSS and HTML

What did you find difficult while building the project? Using flexbox correctly is pretty challenge to me. I find it difficult to put Card and Text in column, then Image and Description in row, and finally centre all the items in the middle of page.

Which areas of your code are you unsure of? This is the first time I use overflow: hidden to hide the two scroll bar on right and bottom.

Do you have any questions about best practices? Desktop-first or mobile-first: Which one is better? Or it depends?