Responsive landing page using css

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

Next time I would start with desktop flow first.

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

Challenge I encounter was to add success subscription note under input field with following reset to original input empty field. I overcome it with using setTimout function in javascript and animation in css.

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

I would like anybody's feedback on my code regarding readibility, structure and so on. I follow easiest projects first in the order they are when filtered in Frontendmentor. I have completed 20 of them, soon moving to junior level of difficulty so anybody's advice I would highly appreciate if someone find a time. I use plain css and vanilla javascript in this stage only.