/prismer-design-md

name: prismer-design-md
scope: coding
category: creative
description: Author/validate/export Google's DESIGN.md token spec files.
version: 1.1.0
author: Hermes Agent
license: MIT
platforms: [linux, macos, windows]
metadata:
  nativeReplaces: [design-md]
  hermes:
    tags: [design, design-system, tokens, ui, accessibility, wcag, tailwind, dtcg, google]
    related_skills: [prismer-popular-web-designs, frontend-design, pkf-svg]

DESIGN.md Skill

DESIGN.md is Google's open spec (Apache-2.0, `google-labs-code/design.md`) for describing a visual identity to coding agents. One file combines:

• **YAML front matter** — machine-readable design tokens (normative values)
• **Markdown body** — human-readable rationale, organized into canonical sections

Tokens give exact values. Prose tells agents *why* those values exist and how to apply them. The CLI (`npx @google/design.md@0.3.0`) lints structure + WCAG contrast, diffs versions for regressions, and exports to Tailwind or W3C DTCG JSON.

When to use this skill

• User asks for a DESIGN.md file, design tokens, or a design system spec
• User wants consistent UI/brand across multiple projects or tools
• User pastes an existing DESIGN.md and asks to lint, diff, export, or extend it
• User asks to port a style guide into a format agents can consume
• User wants contrast / WCAG accessibility validation on their color palette

For purely visual inspiration or layout examples, use `popular-web-designs` instead. For *process and taste* when designing a one-off HTML artifact from scratch (prototype, deck, landing page, component lab), use `claude-design`. This skill is for the *formal spec file* itself.

File anatomy

---
version: alpha
name: Heritage
description: Architectural minimalism meets journalistic gravitas.
colors:
  primary: "#1A1C1E"
  secondary: "#6C7278"
  tertiary: "#B8422E"
  neutral: "#F7F5F2"
typography:
  h1:
    fontFamily: Public Sans
    fontSize: 3rem
    fontWeight: 700
    lineHeight: 1.1
    letterSpacing: "-0.02em"
  body-md:
    fontFamily: Public Sans
    fontSize: 1rem
rounded:
  sm: 4px
  md: 8px
  lg: 16px
spacing:
  sm: 8px
  md: 16px
  lg: 24px
components:
  button-primary:
    backgroundColor: "{colors.tertiary}"
    textColor: "#FFFFFF"
    rounded: "{rounded.sm}"
    padding: 12px
  button-primary-hover:
    backgroundColor: "{colors.primary}"
---

## Overview

Architectural Minimalism meets Journalistic Gravitas...

## Colors

- **Primary (#1A1C1E):** Deep ink for headlines and core text.
- **Tertiary (#B8422E):** "Boston Clay" — the sole driver for interaction.

## Typography

Public Sans for everything except small all-caps labels...

## Components

`button-primary` is the only high-emphasis action on a page...

Token types

| Type | Format | Example | |------|--------|---------| | Color | any CSS color (hex, `rgb()`, `oklch()`, named) | `"#1A1C1E"`, `"oklch(62% 0.18 250)"` | | Dimension | number + unit (`px`, `em`, `rem`) | `48px`, `-0.02em` | | Token reference | `{path.to.token}` | `{colors.primary}` | | Typography | object with `fontFamily`, `fontSize`, `fontWeight`, `lineHeight`, `letterSpacing`, `fontFeature`, `fontVariation` | see above |

Component property whitelist: `backgroundColor`, `textColor`, `typography`, `rounded`, `padding`, `size`, `height`, `width`. Variants (hover, active, pressed) are **separate component entries** with related key names (`button-primary-hover`), not nested.

Canonical section order

Sections are optional, but present ones should appear in this order. The linter flags out-of-order sections (`section-order`, warning) and duplicate headings — consumers per the spec reject duplicates, so fix both before returning the file.

1. Overview (alias: Brand & Style) 2. Colors 3. Typography 4. Layout (alias: Layout & Spacing) 5. Elevation & Depth (alias: Elevation) 6. Shapes 7. Components 8. Do's and Don'ts

Unknown sections are preserved, not errored. Unknown token names are accepted if the value type is valid. Unknown component properties produce a warning.

Workflow: authoring a new DESIGN.md

1. **Ask the user** (or infer) the brand tone, accent color, and typography direction. If they provided a site, image, or vibe, translate it to the token shape above. 2. **Write `DESIGN.md`** in their project root using `write_file`. Always include `name:` and `colors:`; other sections optional but encouraged. 3. **Use token references** (`{colors.primary}`) in the `components:` section instead of re-typing hex values. Keeps the palette single-source. 4. **Lint it** (see below). Fix any broken references or WCAG failures before returning. 5. **If the user has an existing project**, also write Tailwind or DTCG exports next to the file (`tailwind.theme.json`, `tokens.json`).

Workflow: lint / diff / export

The CLI is `@google/design.md@0.3.0` (Node). Use `npx` — no global install needed.

# Validate structure + token references + WCAG contrast
npx -y @google/design.md@0.3.0 lint DESIGN.md

# Compare two versions, fail on regression (exit 1 = regression)
npx -y @google/design.md@0.3.0 diff DESIGN.md DESIGN-v2.md

# Export to Tailwind v3 theme JSON (`tailwind` is a back-compat alias)
npx -y @google/design.md@0.3.0 export --format json-tailwind DESIGN.md > tailwind.theme.json

# Export to a Tailwind v4 CSS @theme block (--color-*, --text-*, --radius-*, ...)
npx -y @google/design.md@0.3.0 export --format css-tailwind DESIGN.md > theme.css

# Export to W3C DTCG (Design Tokens Format Module) JSON
npx -y @google/design.md@0.3.0 export --format dtcg DESIGN.md > tokens.json

# Print the spec itself — useful when injecting into an agent prompt
npx -y @google/design.md@0.3.0 spec --rules-only --format json

All commands accept `-` for stdin. `lint` returns exit 1 on errors (warnings alone exit 0). `export` exits 0 on a successful export regardless of lint findings in the source — run `lint` separately to gate on those. Output is JSON by defaul