ajantoniou/fable-design-system — reverse-engineered prompt

Build me a small open source repo for a Fable style design system that I can plug into AI coding agents like Claude, Cursor, Codex, and Gemini or Antigravity. The goal is not a component library, it is more like a design brain that makes the agent produce much better looking marketing pages and product UI instead of the usual generic defaults.

I want it to push the agent toward warm editorial design, real font pairings, a soft paper like background, one meaningful accent color, fluid type and spacing, pill buttons, subtle shadows, restrained motion, and solid accessibility. It should also tell the agent to define the design system first, then build, then self check contrast and test real responsive breakpoints before saying it is done.

Please include a one command installer, manual install instructions for each agent, project level rule files where that makes sense, and a clear README with before and after visuals and honest caveats about this being a community reconstruction of a style. Look up current docs online if you need to.