CSS Transitions/Animations & JavaScript DOM Manipulation

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.

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.