MozaikaDesign system

Observable — Design System

light · modern · medium · tailwind · confidence 92% · deep decode

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; 8px 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

RoleValue
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

Typography

Spacing

Radii

Shadows (elevation)

Motion

Micro-interactions run at 200ms (dominant) with ease-in-out.

Native design tokens

TokenValue
--black#000
--white#fff
--near-black#1c1c1c
--dark-gray#454545
--mid-gray#6e6e6e
--moon-gray#c4c4c4
--light-gray#e2e2e2
--near-white#f5f5f5
--gray#929292
--silver#e8e8e8

…and 110 more measured on the page.

Button states (measured)

Layout (measured)

Motion choreography (measured)

Load order: div.jsx-3b5ab7e5d596c6f5 → div.jsx-1468fe3ac7fdbbd4×17 → div.jsx-33d4ea7186cd0717×10

Scroll reveal: 3 elements rest at a pre-reveal state.

Responsive (measured)

Per-section tokens (11)

Export: DESIGN.md

# Observable — Design System

> light, modern, medium, tailwind — deep decode (measured live)

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.
- **Page coverage** (full-page screenshot pixels): `#FFFFFF` 46.9% · `#1C1C1C` 35.3% · `#609A96` 10.5% · `#CAE4E6` 7.2%

## Typography

- Heading: **Spline Sans Mono** _(free fallback: JetBrains Mono)_
- Body: **Inter**
- Mono: **__Spline_Sans_Mono_1999fd** _(measured)_

| Role | Size / weight · line-height · tracking |
|------|------------------------------------------|
| hero | 56px / 500 · lh 64px |
| h2 | 40px / 500 · lh 48px |
| body | 20px / 400 · lh 28px |
| small | 18px / 500 · lh 28px |
| eyebrow | 16px / 700 · tracking 1.6px |

- Weight ladder: 400 · 500 · 600 · 700 — use these exact measured weights, not the 400/600 defaults.

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

## Spacing
- base unit: 8px (inferred from the measured scale)
- measured scale: 2px, 8px, 10px, 15px, 16px, 21px, 24px, 32px, 34px, 48px — snap all gaps/padding to these

## Radius
- base: 2px
- button: 0px
- card: 4px
- sharp: 2px

## Buttons

| Button | Fill / text | Border | Radius | Padding | Font | Shadow |
|--------|-------------|--------|--------|---------|------|--------|
| primary | `#FFFFFF` / `#1C1C1C` | none | 0px | 8px 16px 8px 16px | 600 16px | none |
| secondary | `rgba(0, 0, 0, 0)` / `#FFFFFF` | 2px solid rgb(255, 255, 255) | 0px | 20.5px 16px 20.5px 16px | 700 16px | none |

**States (measured, not guessed)**

- primary hover: background `#EEEEEE`
- primary focus: outline `1px auto rgb(16, 16, 16)`
- secondary hover: background `rgba(255, 255, 255, 0.05)`

## Shadows (elevation)
- subtle: `rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0.1) 0px 10px 15px -3px, rgba(0, 0, 0, 0.1) 0px 4px 6px -4px`
- card: `rgba(0, 0, 0, 0.12) 0px 4px 15px 0px`

## Motion
- durations: 200ms (dominant) · 100ms · 150ms
- easings: `ease-in-out` (dominant) · `cubic-bezier(0.4, 0, 0.2, 1)`
- animated properties: opacity, border-color, height, background-color

Micro-interactions use the dominant duration + easing; nothing on the page animates slower than the longest duration above — don't invent springier motion.

## Their own tokens (verbatim from :root)

| Token | Value |
|-------|-------|
| `--black` | `#000` |
| `--white` | `#fff` |
| `--near-black` | `#1c1c1c` |
| `--dark-gray` | `#454545` |
| `--mid-gray` | `#6e6e6e` |
| `--moon-gray` | `#c4c4c4` |
| `--light-gray` | `#e2e2e2` |
| `--near-white` | `#f5f5f5` |
| `--gray` | `#929292` |
| `--silver` | `#e8e8e8` |
| `--light-silver` | `#efefef` |
| `--black-90` | `#16191d` |

_…and 108 more measured on the page._

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

## Layout (measured)
- common grid: 12-col
- nav: 64px sticky

| Section (y) | Height | Cols | Gap | Pad y | Split |
|---|---|---|---|---|---|
| 931 | 693 | 12 | 32 | 0/0 | — |

## Motion choreography (measured)
Load order: `div.jsx-3b5ab7e5d596c6f5` @0ms → `div.jsx-1468fe3ac7fdbbd4`×17 @537ms → `div.jsx-33d4ea7186cd0717`×10 @1068ms
- scroll reveal: 3 elements rest at a pre-reveal state (3 revealed during the drive).

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

## Responsive (measured)
- breakpoints: 450px · 480px · 640px · 768px · 800px · 960px
- mobile (390px): hero 28px · body 14px · nav: hamburger

## 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/ds/observable

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;
  --font-mono: "__Spline_Sans_Mono_1999fd", ui-monospace, monospace;
  /* measured weights: 400, 500, 600, 700 — use these, not 400/600 */
  --text-hero: 56px; --font-weight-hero: 500; --leading-hero: 64px;
  --text-h2: 40px; --font-weight-h2: 500; --leading-h2: 48px;
  --text-body: 20px; --font-weight-body: 400; --leading-body: 28px;
  --text-small: 18px; --font-weight-small: 500; --leading-small: 28px;
  --text-eyebrow: 16px; --font-weight-eyebrow: 700; --tracking-eyebrow: 1.6px;
  --radius-base: 2px;
  --radius-button: 0px;
  --radius-card: 4px;
  --radius-sharp: 2px;
  --shadow-card: rgba(0, 0, 0, 0.12) 0px 4px 15px 0px;
  --shadow-subtle: rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0.1) 0px 10px 15px -3px, rgba(0, 0, 0, 0.1) 0px 4px 6px -4px;
  --color-btn-hover: #EEEEEE;  /* measured primary hover fill */
  --outline-focus: 1px auto rgb(16, 16, 16);  /* measured focus ring */
  --ease-brand: ease-in-out;
  --duration-fast: 100ms;  /* use: duration-[var(--duration-fast)] */
  --duration-base: 150ms;
  --duration-slow: 200ms;
  --spacing: 8px;  /* measured base — drives the p-*/gap-* scale. steps seen on the page: 2, 8, 10, 15, 16, 21, 24, 32, 34, 48px */
}

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;
  --font-mono: "__Spline_Sans_Mono_1999fd", ui-monospace, monospace;
  --text-hero: 56px; --weight-hero: 500; --leading-hero: 64px;
  --text-h2: 40px; --weight-h2: 500; --leading-h2: 48px;
  --text-body: 20px; --weight-body: 400; --leading-body: 28px;
  --text-small: 18px; --weight-small: 500; --leading-small: 28px;
  --text-eyebrow: 16px; --weight-eyebrow: 700; --tracking-eyebrow: 1.6px;
  --radius: 2px;
  --radius-button: 0px;
  --radius-card: 4px;
  --radius-sharp: 2px;
  --shadow-card: rgba(0, 0, 0, 0.12) 0px 4px 15px 0px;
  --shadow-subtle: rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0.1) 0px 10px 15px -3px, rgba(0, 0, 0, 0.1) 0px 4px 6px -4px;
  --btn-bg-hover: #EEEEEE;
  --focus-ring: 1px auto rgb(16, 16, 16);
  --ease: ease-in-out;
  --duration-fast: 100ms;
  --duration-base: 150ms;
  --duration-slow: 200ms;
}

/* their own tokens, verbatim from the site's :root */
:root {
  --black: #000;
  --white: #fff;
  --near-black: #1c1c1c;
  --dark-gray: #454545;
  --mid-gray: #6e6e6e;
  --moon-gray: #c4c4c4;
  --light-gray: #e2e2e2;
  --near-white: #f5f5f5;
  --gray: #929292;
  --silver: #e8e8e8;
  --light-silver: #efefef;
  --black-90: #16191d;
}
/* fonts: Spline Sans Mono may be proprietary — safe free fallback: JetBrains Mono (Google Fonts). Inter — free, on Google. */