A per-business design recipe (palette, type, layout, section variants) applied at render.
A Muse is the design recipe applied to a business site: palette, typography, layout axes, decorative flourishes, and which section variants to use. Stored in the muses table as reading_json, resolved per business, and turned into per-site CSS.
A Muse is often seeded from a Family. The full machinery is the Muse System.