I managed to make it work in what i would say a decent fashion.
I'm not sure how to make the backend calculator functionality of it very well, I feel like I made it in a very hacky way that works but most likely has a very large amount of issues and bugs.
This is the first time i tried implementing any sort of themes and also first time storing a variable in localstorage. I feel like it got a little messy with different small elements changing color for each theme making me create very specific css variables. Is this the correct way of doing this? Or is there a better way that I didn't realise.
Over all I'm happy with how this turned out and would love it if you have any criticisms, pointers or thought for me.
Thanks for looking and reading!