Social Profile Challenge with vanilla html+css

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

Most proud of: Understand the structure from the get-go and an increased speed of doing this challenge, compared to the previous ones.

What would I do differently: Use the flexbox properties more efficiently, rather than relying on the old way of styling/setting boundaries.

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

The most conundrum I have is about setting the width/responsiveness and the general card margin. This should be responsive across screen widths, but I don't grasp which is the actual standard/expectation for it to be considered like so.