The silly motivation is that I wanted to remove `.prettierignore`,
which just exists to omit that one folder from `npm run format`. But it
also seems like this is the standard place to put them—a standard
created long after we first set this up lol
This required a buncha fixes to how SASS scoping works! Needed to add a bunch of imports for stuff that previously would get read from the global scope by being imported *after* the constants and mixins etc.
There's clearly a lot of refactor opportunity here, but I'm not gonna worry about it!!
