Tip Calculator Project in OOP

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

Honestly, I'm proud that I was able to finish this project (yes I am a beginner, I have been on and off learning frontend, and now I got the time to learn it all the way through finishing the fundamentals of JavaScript).

EDIT: I completely refactored my solution. After learning how to do OOP in JavaScript, I realized I can use that programming paradigm to this project and to practice my JS skills overall. In conclusion, I think this current one is far better than the previous solution that I had posted here before.

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

Starting this project, I thought this is going to be a breeze since I already had experienced making the same project with Python and JavaScript (both in console-based learning).

One specific challenge I encountered was after I thought I was done with the project that I noticed the main functionality of the website was not working properly on mobile phones. I did some research and found out that there was far better method to choose than the ones I already know.

I've learned a lot of things when doing this project, not just of how JavaScript works but also how doing the frontend can be so complex that looking for simplicity is the best answer.