Responsive design using Flexbox

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

I took 2 days to finish it since it took me some time to do the JavaScript part, as I haven't written code in a while and couldn't remember some functions, but I helped myself a bit by searching on the internet and finished it without any problems.

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

I didn't know how to make the form and success cards switch between each other once the email was entered correctly, but I helped myself with a similar project I found online and realized that the solution was easier than I thought. With 3 lines of code in JavaScript and adding some tags to the HTML, I was able to solve it.

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

I would like to know if the JavaScript is well-coded and if the order of the lines is correct. I would also like to know if there is anything to correct in the CSS.