Vellum reading

Vellum's signature skill — measured prose, not dashboards.

Rules

1. Pick typesetClass / reading-ui / reading-prose before styling tags.
2. Measure ~65ch; never exceed 80ch.
3. Docs/help = sans reading-ui; essays = reading-prose serif.
4. Streaming-stable — reserve space; no CLS on tokens.
5. Brand for links/CTA only — not paragraph color.
6. No activity pastels, Bionic Reading, or sepia gimmicks in prose.
7. Prove against /vellum reading demo.

Done

• Matches contracts/vellum/DESIGN.md
• Long-form never ships as full-bleed text-sm