DADS — Digital Agency Design System

Knowledge for making output look and behave like the Digital Agency Design System (デジタル庁デザインシステム, DADS) — Japan's government design system, MIT-licensed tokens and components published by digital-go-jp.

Scope: visual authority only

This skill answers one question: what does DADS-compliant look like, and how do I get there from primary sources? It owns colors, typography, component markup, usage rules, and the compliance policy below.

It deliberately does not own structure or medium. Compose it:

• New artifact → artifact-design (and the Artifact tool's constraints) own the medium; this skill owns the look. See references/artifact.md for where the two collide (CSP, dark theme).
• Existing frontend restyle → the codebase owns structure; change only what the three-layer check below flags as deviating.

The three-layer model

DADS compliance has three layers. Applying only the first produces "なんちゃって DADS" — colors that look right on markup that an official page would never emit. Real deviations (a table wrapped in a rounded container, a bold chip label) are invisible at the token layer and only surface when compared against official component CSS.

Work top-down through all three for anything user-facing. Token-only application is acceptable solely for throwaway internal sketches.

Key token values (design-tokens 2.0.1)

The full file is references/tokens.css (226 lines, pinned verbatim). The values that make or break the DADS look:

• Key color: --color-key-* = blue family; the anchor is blue-900 #0017c1 (the Digital Agency blue).
• Semantic: error-1 = red-800 #ec0000 / warning-yellow-1 = yellow-700 #b78f00 / success-1 = green-600 #259d63.
• Font: 'Noto Sans JP', ... — mono is 'Noto Sans Mono'.
• Body text: 16px, line-height 1.75, letter-spacing 0.02em — omit the letter-spacing and nothing will read as DADS no matter how right the colors are.
• Heading sizes: 64/57/45/36/32/28/24/20/18/16 (there is no 22).
• Radius scale: 4/6/8/12/16/24/32/full.

Components

Read references/components.md before touching any component. The one rule worth stating here: port official dads-* class names and CSS verbatim — never transcribe values into homemade classes, or the result can no longer be diffed against the official source when it drifts.

Pick components from references/guidelines/components-index.md (the official catalog). Per-component usage guidelines for the ones already battle-tested (notification-banner, table, heading) plus color/typography foundations are in references/guidelines/.

Policy (always in force)

• No impersonation. Tokens and components are MIT; the Digital Agency's logo, illustration assets, and name are not part of that grant. Never produce something that reads as an actual Digital Agency page. DADS-styled ≠ Digital-Agency-branded.
• Label extensions as extensions. Official DADS is light-only (white hardcoded). A dark theme is a DADS-compliant extension, not official DADS — derive it per references/artifact.md and say so in the page footer or equivalent.
• Attribution for guideline excerpts follows the official notice: https://design.digital.go.jp/dads/introduction/notices/ — each bundled guideline file keeps its source_url frontmatter for this reason.

Refreshing pinned sources

The pins keep this skill reproducible; refresh deliberately, not per-use.

# tokens — check the published version before overwriting the pin (currently 2.0.1)
curl -sL https://unpkg.com/@digital-go-jp/design-tokens@latest/package.json | jq -r .version
curl -sL https://unpkg.com/@digital-go-jp/design-tokens@latest/dist/tokens.css

# guidelines — the ZIP link is dated with no latest-URL; scrape it from the resources page
# (bundled copies are from dads-markdown-20260805.zip)
curl -sL https://design.digital.go.jp/dads/resources/ | grep -oE '/dads/dads-markdown-[0-9]+\.zip'

Components are fetched live (see references/components.md) rather than pinned — the set is large, and live fetch preserves diff-ability against the current official source.

Dead ends (do not revisit)

• design.digital.go.jp/llms.txt — 404, does not exist.
• tokens.css at the npm package root — the real file is under dist/; list with https://unpkg.com/@digital-go-jp/design-tokens@latest/?meta first.
• digital-go-jp/tailwind-theme-plugin — a repackaging of the tokens, zero new information unless the target project already uses Tailwind.
• components/chip-label guideline — official doc is a "準備中" stub; the porting notes in references/components.md are the best available source.