Context
As noted in this task and previous documentation, we want to add a new spacing token that is more appropriate for a max-width on certain forms. After discussion, we have agreed that this new spacing token should be 40rem (or 640px in our default Codex theme).
Acceptance criteria
- New spacing token has been added in code
- New spacing token has been added in Figma
- Docs site and Figma spec have been updated to reflect the change
- Form guidelines (including images) have been updated in Figma and on the docs site