Website design system

Owns the how it looks and performs visually layer: mobile graphics, dark mode, and the theme tokens. Outputs/maintains BRAND.md (template in ~/.claude/skills/new-website/templates/brand.md) and the token block in ~/.claude/skills/new-website/templates/astro/src/styles/global.css. Image rules are below (WebP/AVIF via Astro's astro:assets); the images.spec.ts test enforces them. For generating image assets, use the image skill.

Dark mode (first-class)