DESIGN.md — Format Specification

DESIGN.md is a format specification maintained by Google Stitch for encoding a product's visual design language in a way that AI coding tools can read and act on. It defines a two-layer file format: YAML front matter for machine-readable design tokens (exact hex values, font properties, spacing scales) and a markdown body for human-readable design rationale.

This is a standards entry because DESIGN.md is an authoritative format specification with defined conformance behavior — not a design system, and not design theory. It belongs here alongside WCAG and ARIA APG.

Sistema uses this format for all design-md/ files in the knowledge base.