Claude — decoded design system

claude.ai · light · professional · custom · deep decode — measured live

Claude's design system, decoded live by Mozaika: measured color roles, type scale, buttons with real hover/focus states, motion and the brand's own tokens.

Open in Mozaika →

This is a static, crawlable rendering for search & AI engines. The interactive version — filters, live decode console, copy & export — is at https://mozaika.design/decode/claude.ai.

Decoded design system

Claude's decoded design system: background #FFFFFF, text #0B0B0B, accent #0B0B0B, link #000000, primary #000000; type scale h1 13px / h2 20px / body 13px; 4px spacing base; 7px base radius. The single interactive/action color is #0B0B0B — used only on interactive or must-notice elements (buttons, links, key highlights), never on large fills.

Color roles

Using these colors

• Action color #0B0B0B — the single interactive color; only on things you click or must notice, never large fills.
• primary, link are all #000000 — one role, not several (the action color).
• accent, button_bg are all #0B0B0B — one role, not several (the action color).
• accent #0B0B0B — THE accent / action color — interactive & must-notice only (buttons, links, focus, one key highlight); never large fills or backgrounds. Scarcity is what makes it read as designed.

Typography

• Heading: Anthropic Serif
• Body: Anthropic Sans
• h1: 13px
• h2: 20px
• body: 13px

Spacing

• base unit: 4px
• scale: 2px, 4px, 6px, 8px, 12px, 16px, 24px, 32px

Radii

• base: 7px
• button: 8px

Native design tokens

…and 6 more measured on the page.

Button states (measured)

• primary focus: outline 1px auto rgb(16, 16, 16)

Motion choreography (measured)

Load order: div

Themes

dark counterpart: background #1A1A19, text #F0EFEC.

Responsive (measured)

• mobile (390px): nav inline

Install it

Drop this measured system into any shadcn/Tailwind project in one command:

npx shadcn add https://mozaika.design/r/decode/claude.ai

Or as a Meta Astryx theme — a ready defineTheme file with the measured hover/press states baked in:

curl -o src/themes/claude.theme.ts https://mozaika.design/api/astryx/decode/claude.ai.ts

registry item · astryx theme · or query it over MCP: get_design_system("Claude")

Export: DESIGN.md

# Claude — Design System

> light, professional, low, custom — deep decode (measured live)

## Colors

| Role | Value |
|------|-------|
| bg | `#FFFFFF` |
| surface | `#F0F0F0` |
| border | `#DADADA` |
| text | `#0B0B0B` |
| text_muted | `#676767` |
| primary | `#000000` |
| accent | `#0B0B0B` |
| link | `#000000` |
| button_bg | `#0B0B0B` |
| button_text | `#FFFFFF` |

**Using these colors**

- **Action color** `#0B0B0B` — the single interactive color; it appears only on things you click or must notice (buttons, key highlights), never on large fills or backgrounds.
- `primary`, `link` are all `#000000` — one role, not several.
- `accent`, `button_bg` are all `#0B0B0B` — one role, not several (your action color).
- **accent** `#0B0B0B` — THE accent / action color — interactive & must-notice only (buttons, links, focus, one key highlight); never large fills or backgrounds. Scarcity is what makes it read as designed.
- **Page coverage** (full-page screenshot pixels): `#FFFFFF` 98.8% · `#121212` 0.3% · `#B0ACAA` 0.2% · `#BFC0C1` 0.2% — the action color covers ~0.3% of the page; keep it that scarce.

## Typography

- Heading: **Anthropic Serif** _(free fallback: Newsreader)_
- Body: **Anthropic Sans** _(free fallback: Newsreader)_
- h1: 13px
- h2: 20px
- body: 13px

> **Fonts —** Anthropic Serif may be proprietary — safe free fallback: Newsreader (Google Fonts). Anthropic Sans may be proprietary — safe free fallback: Newsreader (Google Fonts).

## Spacing
- base unit: 4px
- scale: 2px, 4px, 6px, 8px, 12px, 16px, 24px, 32px

## Radius
- base: 7px
- button: 8px

## Buttons

| Button | Fill / text | Border | Radius | Padding | Font | Shadow |
|--------|-------------|--------|--------|---------|------|--------|
| primary | `#0B0B0B` / `#FFFFFF` | 1px solid rgba(0, 0, 0, 0) | 8px | 8px 16px 8px 16px | 400 14px | none |

**States (measured, not guessed)**

- primary focus: outline `1px auto rgb(16, 16, 16)`

## Their own tokens (verbatim from :root)

| Token | Value |
|-------|-------|
| `--bg` | `#fff` |
| `--fg` | `#0b0b0b` |
| `--mut` | `#52514e` |
| `--spin` | `#898781` |
| `--line` | `#0b0b0b1a` |
| `--div` | `#0b0b0b0d` |
| `--bord` | `#0b0b0b33` |
| `--hov` | `#0b0b0b0d` |
| `--surf` | `#fff` |
| `--brand` | `#c6613f` |
| `--primary` | `#0b0b0b` |
| `--on-primary` | `#fff` |

_…and 4 more measured on the page._

Prefer these names when extending their system — it's the brand's actual vocabulary.

## Layout (measured)

| Section (y) | Height | Cols | Gap | Pad y | Split |
|---|---|---|---|---|---|
| 48 | 852 | — | — | 0/0 | — |

## Motion choreography (measured)
Load order: `div` @0ms

Rebuild the timeline, not just the durations — order, delays and staggers above are the choreography.

## Themes (both measured)
- dark counterpart: bg `#1A1A19` · text `#F0EFEC`
- tokens that flip between modes:
  - `--bg`: `#fff` → `#1a1a19`
  - `--fg`: `#0b0b0b` → `#f0efec`
  - `--mut`: `#52514e` → `#c3c2b7`
  - `--line`: `#0b0b0b1a` → `#ffffff1a`
  - `--div`: `#0b0b0b0d` → `#ffffff0d`
  - `--bord`: `#0b0b0b33` → `#fff3`
  - `--hov`: `#0b0b0b0d` → `#ffffff13`
  - `--surf`: `#fff` → `#20201f`

## Responsive (measured)
- mobile (390px): body 13px · nav: inline

## How to apply
Paste the Tailwind `@theme` (or CSS variables) as your base, then build each
section to its spec — verify every color, radius, and font against these tokens.
Hover/focus states, shadows and motion timings above are measured from the live page — match them exactly, don't re-guess them.

---

> **Decoded with Mozaika** — measured live, not guessed. Full decoded design system + one-command install: mozaika.design/decode/claude.ai

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An automated reading of Claude's publicly-visible CSS (colors, fonts, spacing, motion) — not affiliated with claude.ai. No screenshots stored. Removal requests: hello@mozaika.design.