Calculator, all functions, grid layout, constructor functions

I made this project using constructor functions, something I had never used before, so I had to look them up and watch some tutorials, but I think it was worth it, because now I have some knowledge about key components of JS such as constructors, classes and .this keyword. I started to work on this project with a bunch of if statements and innertexts, but I stopped mid project as some features were weird to implement in this format, and that's the reason I looked up at other ways of doing it. Worth it overall! For the theme changing part it wasn't difficult at all, just a bit of a mess with all the classes to add to the css file in order to change the theme.