Responsive testimonials grid section using HTML and CSS

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

First time I've used grids to place elements, and I'm pretty proud of the end result.

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

Responsive with grids is still a bit vague, so I usually use flexbox, even if the result isn't perfect with that either.

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

I'd love some tips on responsive, whether it's breakpoints, habits to adopt, etc.