Update line height in global spec sheet

## Background
Awhile back I created a universal global spec XD file that can be plugged into any working XD file, and is managed through Abstract. I wrangled the color specs in the pass: updating the colors to match the USWDS update, and also updated the variable names. This helps with consistency across branches/files, and managing them at a global level.

## The ask
In this update, let's go through and finish out the line height portion of typesetting. Lately I'm constantly having to override the main state because there was an arbitrary line height inherited from a previous attempt.

- [ ] Update line height for all system sizes

## Working files
💎 Abstract branch: https://share.goabstract.com/00c13cb9-1bd8-4608-830c-ca8413778166