Interactive Credit Card

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

I'm proud of the overall website, since in never used JS in a project before, but the CSS and JS is not very clear and i would have a hard time trying to update the website.

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

:user-invalid I didn't knew of to check the format of input values, I used RegEx to do it but I could have done it more easily by using :user-invalid css pseudo-class, to change the color of the borders to red, maybe even to display the errors messages.

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

I would like to know if the way i write JS is good, or what can i improve, and same thing for css, i feel like my code is not very organized.