Problem:
Loading unnecessary files for bootstrap.

Solution:
Update bootstrap version and remove old files.
Bootstrap now includes popperjs. Doesn't need jquery anymore.
Bootstrap now includes its own reboot. Doesn't need normalize.css anymore.

Problem:
Ruby version in nix-shell is too old to build the site.

Solution:
Update ruby version and nix-shell commands.

Problem:
Lato font is no longer being used.
Inter font is not being loaded.
No difference between serif and sans-serif.

Solution:
Remove old files.
Update variables to load Inter font properly.
Use only sans-serif fonts.

Problem:
New Bootstrap update broke navbar styling.

Solution:
Update navbar to match previous styling.
Clean up a bit.

Problem:
Don't need unminified versions.

Solution:
Remove unminified versions.