style(box): semantic token updates

[ju-Skinner]

Description

Removes most uses of CSS Custom Props in favor of semantic tokens

Fixes #(issue)

Type of change

• Visual Changes

How Has This Been Tested?

• unit tests
• e2e tests
• accessibility tests
• tested manually
• other: Storybook

Checklist:

If not applicable, leave options unchecked.

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes
• Design has QA'ed and approved this PR

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues found.

Scanned Manifest Files

[netlify]

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