All solutions

First time I'm happy with how a site turned out! The only thing I couldn't figure out yet is how to get rid of the grey outline around the button in active state. Any advice is welcome, as always. :)

In the first attempt, I didn't use Grid or Flexbox, nor did I have any idea how to make the page responsive for mobile. Hope I got a little closer to the design now.

Questions I came up with:

1. I read somewhere that I should start with the mobile design and work up to desktop from there. True? I have a feeling I bloated the css by starting with desktop.
2. If I had to do it again, I think I'd rather put the footer in a .footer div instead of using the html tag <footer> to make placement in the grid easier. Good idea or not recommended due to the semantic function of <footer>?

First time adding a solution, so I hope the links work okay. Sort of works, I think, but I'm still having trouble with positioning. :/ Any tips on that are much appreciated!

I also couldn't figure out how to move the "per month" text a little higher. Should I put that in a separate div from the amount and try positioning it that way?