Responsive calculator app using tables and some basic JS

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

My greatest achievement with this project is learning how to change web application themes and saving those settings in local storage. Next time I would organise my styles better and take some more time for my JS script to be more readable and efficient.

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

The greatest challenge was the JS script because of the logic of this calculator. I finally did it the easy way, but I had a plan about doing it the way regular calculator works - unfortunately I gave up :)

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

I would like to know, what is the best way of creating the keypad button area? I did it using tables because I knew how to merge some columns/rows together. Would it be better to create such areas with display: grid?