Add shadow tokens to theme #103
Description
From Brandon:
0 1px 3px rgb(0 0 0 / 15%) (small, adds some outline without having a border, used for things like dropdowns)
0 3px 6px rgb(0 0 0 / 25%) (for "higher" items or things that need more focus, used on buttons or cards sometimes)
0 10px 30px rgb(0 0 0 / 50%) (used for modals and things like that)
I don't use many at the moment, so something like the Radix UI ones are a bit too granular for what I need, but it might be good for a different project.