Font weights

The framework exposes a small set of weights:

• --font-weight (400) — body default
• --font-weight-medium (500) — slightly heavier than body, for nav links
• --font-weight-strong (650) — emphasis, prose headings, badges, tabs, table headers
• --font-weight-bold (700) — the strongest weight exposed, used by the navbar brand and the accordion summary

No --font-weight-light. Light weights depend on the typeface, are rarely a good default, and add surface area without a recurring need. These weights are also the values used by components. Components do not use literal font-weight: 600 or font-weight: 750; they reference the tokens. Theme authors can re-map them in one place.