Wraps your HTML artifacts with a live control panel that lets users adjust accent color, type scale, density, light/dark mode, and motion without re-prompting Claude. Changes rewrite CSS custom properties in real time and persist to localStorage across refreshes. Use it when someone likes your design 80% of the way but wants to dial in the last 20% themselves, or when you're demoing a brand system and want viewers to feel the variants live. Integrates with the Open Design viewer toolbar via postMessage or class-based protocols. The five-knob pattern is opinionated: curated color swatches instead of free pickers, ±15% scale limits to prevent layout breakage, and motion that respects prefers-reduced-motion.
npx skills add https://github.com/nexu-io/open-design --skill tweaks