Courier — Design System

Name: Courier design system
Creator: Mozaika
Keywords: design system, design tokens, Courier, dark, custom

dark · modern · medium · custom · confidence 92%

Courier composes notifications-for-humans-and-agents in GitHub's open-source Mona Sans: 64px/400 white headlines on near-black #0A0A0A, 15-16px body, and barely-there translucent buttons at 6px radius. Inbox UI panels and API snippets alternate like a conversation between designer and developer — messaging infrastructure with its volume knob deliberately at four.

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/ds/courier.

Tokens

Courier's decoded design system: background #0A0A0A, text #ECECEE, accent #0000EE, link #083218, primary #0000EE; type scale h1 64px / h2 40px / body 14px; 4px spacing base; 12px base radius. The single interactive/action color is #E2E2E2 — used only on interactive or must-notice elements (buttons, links, key highlights), never on large fills.

Color roles

Role	Value
bg	`#0A0A0A`
surface	`#171717`
border	`#2B2B2C`
text	`#ECECEE`
text_muted	`#969697`
primary	`#0000EE`
accent	`#0000EE`
link	`#083218`
secondary	`#00B046`
button_bg	`#E2E2E2`
button_text	`#0000EE`

Using these colors

Action color #E2E2E2 — the single interactive color; only on things you click or must notice, never large fills.
primary, accent are all #0000EE — one role, not several (the action color).
accent #0000EE — accent for emphasis — keep it rare on the page.
link #083218 — fails contrast on the background (~1.4:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference).
secondary #00B046 — optional secondary accent — LOW decode confidence; use rarely (a status color or a single decorative moment) or omit it entirely. Prefer one accent unless the reference clearly shows two.

Typography

Heading: Mona Sans
Body: Mona Sans Variable
h1: 64px
h2: 40px
body: 14px

Spacing

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

Radii

base: 12px
button: 6px

Shadow

rgba(0, 0, 0, 0.12) 0px 1px 1px 0px

Per-section tokens (12)

Export: DESIGN.md

# Courier — Design System

> dark, modern, medium, custom

Courier composes notifications-for-humans-and-agents in GitHub's open-source Mona Sans: 64px/400 white headlines on near-black #0A0A0A, 15-16px body, and barely-there translucent buttons at 6px radius. Inbox UI panels and API snippets alternate like a conversation between designer and developer — messaging infrastructure with its volume knob deliberately at four.

## Colors

| Role | Value |
|------|-------|
| bg | `#0A0A0A` |
| surface | `#171717` |
| border | `#2B2B2C` |
| text | `#ECECEE` |
| text_muted | `#969697` |
| primary | `#0000EE` |
| accent | `#0000EE` |
| link | `#083218` |
| secondary | `#00B046` |
| button_bg | `#E2E2E2` |
| button_text | `#0000EE` |

**Using these colors**

- **Action color** `#E2E2E2` — the single interactive color; it appears only on things you click or must notice (buttons, key highlights), never on large fills or backgrounds.
- `primary`, `accent` are all `#0000EE` — one role, not several.
- **accent** `#0000EE` — accent for emphasis — keep it rare on the page.
- **link** `#083218` — fails contrast on the background (~1.4:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference).
- **secondary** `#00B046` — optional secondary accent — LOW decode confidence; use rarely (a status color or a single decorative moment) or omit it entirely. Prefer one accent unless the reference clearly shows two.

## Typography

- Heading: **Mona Sans** _(free fallback: Newsreader)_
- Body: **Mona Sans Variable** _(free fallback: Newsreader)_
- h1: 64px
- h2: 40px
- body: 14px

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

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

## Radius
- base: 12px
- button: 6px

## Primary button
- bg `#E2E2E2` · text `#0000EE` · radius 6px

## 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.

Export: Tailwind v4 (@theme)

@theme {
  /* action color #E2E2E2 — the one interactive color; buttons/links/emphasis only, never large fills. */
  --color-bg: #0A0A0A;
  --color-surface: #171717;
  --color-border: #2B2B2C;
  --color-text: #ECECEE;
  --color-text-muted: #969697;
  --color-primary: #0000EE;  /* a brand color — but the call-to-action uses #E2E2E2, not this. */
  --color-accent: #0000EE;  /* accent for emphasis — keep it rare on the page. */
  --color-link: #083218;  /* fails contrast on the background (~1.4:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference). */
  --color-secondary: #00B046;  /* optional secondary accent — LOW decode confidence; use rarely (a status color or a single decorative moment) or omit it entirely. Prefer one accent unless the reference clearly shows two. */
  --color-button-bg: #E2E2E2;  /* primary-button fill — the main call-to-action color. */
  --color-button-text: #0000EE;
  /* fonts: Mona Sans may be proprietary — safe free fallback: Newsreader (Google Fonts). Mona Sans Variable may be proprietary — safe free fallback: Newsreader (Google Fonts). */
  --font-heading: "Mona Sans", "Newsreader", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-body: "Mona Sans Variable", "Newsreader", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --text-h1: 64px;
  --text-h2: 40px;
  --text-body: 14px;
  --radius-base: 12px;
  --radius-button: 6px;
  --spacing-1: 2px;
  --spacing-2: 4px;
  --spacing-3: 6px;
  --spacing-4: 8px;
  --spacing-5: 12px;
  --spacing-6: 16px;
  --spacing-7: 24px;
  --spacing-8: 32px;
}

Export: CSS variables

:root {
  /* action color #E2E2E2 — the one interactive color; buttons/links/emphasis only, never large fills. */
  --bg: #0A0A0A;
  --surface: #171717;
  --border: #2B2B2C;
  --text: #ECECEE;
  --text-muted: #969697;
  --primary: #0000EE;  /* a brand color — but the call-to-action uses #E2E2E2, not this. */
  --accent: #0000EE;  /* accent for emphasis — keep it rare on the page. */
  --link: #083218;  /* fails contrast on the background (~1.4:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference). */
  --secondary: #00B046;  /* optional secondary accent — LOW decode confidence; use rarely (a status color or a single decorative moment) or omit it entirely. Prefer one accent unless the reference clearly shows two. */
  --button-bg: #E2E2E2;  /* primary-button fill — the main call-to-action color. */
  --button-text: #0000EE;
  --font-heading: "Mona Sans", "Newsreader", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-body: "Mona Sans Variable", "Newsreader", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --radius: 12px;
  --radius-button: 6px;
}
/* fonts: Mona Sans may be proprietary — safe free fallback: Newsreader (Google Fonts). Mona Sans Variable may be proprietary — safe free fallback: Newsreader (Google Fonts). */