Observable — Design System

Name: Observable design system
Creator: Mozaika
Keywords: design system, design tokens, Observable, light, tailwind

light · modern · medium · tailwind · confidence 92%

Observable headlines in a monospace: Spline Sans Mono at 56px/500 ('Not your typical notebook') with Inter at 20px for the reading, zero-radius surfaces, and live D3 visualizations providing the only decoration. Setting display type in mono is the whole brand argument — this is a canvas where code and chart are the same material.

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/observable.

Tokens

Observable's decoded design system: background #F5F5F5, text #1C1C1C, accent #1C1C1C, link #37D5BE, primary #1690F6; type scale h1 56px / h2 40px / body 20px; 4px spacing base; 2px base radius. The single interactive/action color is #1C1C1C — used only on interactive or must-notice elements (buttons, links, key highlights), never on large fills.

Color roles

Role	Value
bg	`#F5F5F5`
surface	`#E7E7E7`
border	`#D4D4D4`
text	`#1C1C1C`
text_muted	`#6E6E6E`
primary	`#1690F6`
accent	`#1C1C1C`
link	`#37D5BE`
secondary	`#FFFF00`
button_bg	`#1C1C1C`
button_text	`#FFFFFF`

Using these colors

Action color #1C1C1C — the single interactive color; only on things you click or must notice, never large fills.
accent, button_bg are all #1C1C1C — one role, not several (the action color).
accent #1C1C1C — 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.
primary #1690F6 — a brand color — but the call-to-action uses #1C1C1C, not this.
link #37D5BE — fails contrast on the background (~1.7:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference).
secondary #FFFF00 — 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: Spline Sans Mono
Body: Inter
h1: 56px
h2: 40px
body: 20px

Spacing

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

Radii

base: 2px
button: 0px

Per-section tokens (11)

Export: DESIGN.md

# Observable — Design System

> light, modern, medium, tailwind

Observable headlines in a monospace: Spline Sans Mono at 56px/500 ('Not your typical notebook') with Inter at 20px for the reading, zero-radius surfaces, and live D3 visualizations providing the only decoration. Setting display type in mono is the whole brand argument — this is a canvas where code and chart are the same material.

## Colors

| Role | Value |
|------|-------|
| bg | `#F5F5F5` |
| surface | `#E7E7E7` |
| border | `#D4D4D4` |
| text | `#1C1C1C` |
| text_muted | `#6E6E6E` |
| primary | `#1690F6` |
| accent | `#1C1C1C` |
| link | `#37D5BE` |
| secondary | `#FFFF00` |
| button_bg | `#1C1C1C` |
| button_text | `#FFFFFF` |

**Using these colors**

- **Action color** `#1C1C1C` — the single interactive color; it appears only on things you click or must notice (buttons, key highlights), never on large fills or backgrounds.
- `accent`, `button_bg` are all `#1C1C1C` — one role, not several (your action color).
- **accent** `#1C1C1C` — 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.
- **primary** `#1690F6` — a brand color — but the call-to-action uses #1C1C1C, not this.
- **link** `#37D5BE` — fails contrast on the background (~1.7:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference).
- **secondary** `#FFFF00` — 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: **Spline Sans Mono** _(free fallback: JetBrains Mono)_
- Body: **Inter**
- h1: 56px
- h2: 40px
- body: 20px

> **Fonts —** Spline Sans Mono may be proprietary — safe free fallback: JetBrains Mono (Google Fonts). Inter — free, on Google.

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

## Radius
- base: 2px
- button: 0px

## Primary button
- bg `#1C1C1C` · text `#FFFFFF` · radius 0px

## 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 #1C1C1C — the one interactive color; buttons/links/emphasis only, never large fills. */
  --color-bg: #F5F5F5;
  --color-surface: #E7E7E7;
  --color-border: #D4D4D4;
  --color-text: #1C1C1C;
  --color-text-muted: #6E6E6E;
  --color-primary: #1690F6;  /* a brand color — but the call-to-action uses #1C1C1C, not this. */
  --color-accent: #1C1C1C;  /* 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. */
  --color-link: #37D5BE;  /* fails contrast on the background (~1.7:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference). */
  --color-secondary: #FFFF00;  /* 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: #1C1C1C;  /* primary-button fill — the main call-to-action color. */
  --color-button-text: #FFFFFF;
  /* fonts: Spline Sans Mono may be proprietary — safe free fallback: JetBrains Mono (Google Fonts). Inter — free, on Google. */
  --font-heading: "Spline Sans Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-body: "Inter", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --text-h1: 56px;
  --text-h2: 40px;
  --text-body: 20px;
  --radius-base: 2px;
  --radius-button: 0px;
  --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 #1C1C1C — the one interactive color; buttons/links/emphasis only, never large fills. */
  --bg: #F5F5F5;
  --surface: #E7E7E7;
  --border: #D4D4D4;
  --text: #1C1C1C;
  --text-muted: #6E6E6E;
  --primary: #1690F6;  /* a brand color — but the call-to-action uses #1C1C1C, not this. */
  --accent: #1C1C1C;  /* 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. */
  --link: #37D5BE;  /* fails contrast on the background (~1.7:1) — this is a dark UI color, NOT a readable link; use the text or action color for links (verify against the reference). */
  --secondary: #FFFF00;  /* 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: #1C1C1C;  /* primary-button fill — the main call-to-action color. */
  --button-text: #FFFFFF;
  --font-heading: "Spline Sans Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-body: "Inter", system-ui, -apple-system, 'Segoe UI', sans-serif;
  --radius: 2px;
  --radius-button: 0px;
}
/* fonts: Spline Sans Mono may be proprietary — safe free fallback: JetBrains Mono (Google Fonts). Inter — free, on Google. */