CSS Transitions/Animations & JavaScript DOM Manipulation

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

I just recently learned how Construction function works and how does using prototype, setTimeout (); and the addEventListener(); but I still have so many stuff regarding Object methods that I couldn't wrap my head around it. So while I was researching I discovered Frontend Mentor, and made me realized to fully understand the courses that I'm learning, I have to apply it in real time. So, if I have to tell someone who is starting to learn how to code, a beginner like me. I would tell them that before moving onto the next lesson, they should try Frontend Mentor and apply what you have learned.

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

GitHub repository process(lol). I know I shouldn't have put a js on this challenge, but I was really having a hard time understanding the Higher order functions, and this challenge is perfect to apply and to understand those js functions. Also, I almost forgot how to do the basics of CSS, so this challenge is perfect for a refresher on flexbox, CSS grid, padding etc.