Duck Theme

duck/ui theme: dark-first canvas, duck-lime primary, holographic accents. Installs the full shadcn CSS-variable contract plus the holo utilities, the display scale, the control-typography tokens, the motion vocabulary and a print layer that re-asserts the light palette on paper, so every existing shadcn component is duck-styled with no markup changes — and so a different theme can undo the duck styling without touching any. It declares no typefaces: --font-sans and --font-mono stay Tailwind's, and --font-display follows --font-sans until you point it at a display face.