Clipboard landing page almost pixel perfect :)))

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

This is my first landing page that I created uing html and css. There was tries before, but they was clunky and wasn't responsive at all.

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

My biggest problem now is how use ems and rems and % correctly and also choosing good margins between elements.

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

What the best ways to use relative units like em and rem, I know that its useful when you build responsive layouts (always useful then). But I cant tell what size would be element at the start. Maybe you should declare font-size in the body element (For example 16px) or its good to write 1rem?