> Atmospheric study inspired by GOV.UK's publicly visible design language. Void Energy is not affiliated with, endorsed by, sponsored by, or licensed by GOV.UK. The downloadable atmosphere file contains color, motion, and typographic-rhythm tokens only — no brand logos, marks, or proprietary assets. All trademarks are the property of their respective owners.

---

---
name: GOV.UK
version: alpha
description: GOV.UK's citizen-service reading — pure-white canvas, gov.uk link blue #1d70b8 as primary, GDS "Start now" green #00703c as success- secondary, deep near-black #0b0c0c ink at WCAG-AAA contrast. The public-service register: constraint-driven layout, accessibility- first chrome, near-zero radii (the famous focus-ring is a literal yellow box, not a curve). Lexend stands in for GDS Transport at the rendering level — both typefaces optimize for reading proficiency above editorial flourish. Distinguished from peer institutional brands (bmw-institutional-light / stripe-modern- light / visa-cardface-light) by typographic register (accessibility-optimized Lexend vs corporate grotesque) and by chrome (zero-radii civic vs modern-rounded SaaS).

colors:
  primary: "#1d70b8"
  secondary: "#00703c"
  neutral: "#6f777b"
  surface: "#ffffff"
  surface-container: "#ffffff"
  on-surface: "#0b0c0c"
  on-surface-variant: "#505a5f"
  outline: "#C9CACA"
  error: "#a60000"

typography:
  display-lg:
    fontFamily: "'Inter', sans-serif"
    fontSize: 56px
    fontWeight: 700
    lineHeight: 1.1
    letterSpacing: "-0.02em"
  headline-lg:
    fontFamily: "'Inter', sans-serif"
    fontSize: 40px
    fontWeight: 600
    lineHeight: 1.15
    letterSpacing: "-0.015em"
  headline-md:
    fontFamily: "'Inter', sans-serif"
    fontSize: 32px
    fontWeight: 600
    lineHeight: 1.2
    letterSpacing: "-0.01em"
  headline-sm:
    fontFamily: "'Inter', sans-serif"
    fontSize: 24px
    fontWeight: 600
    lineHeight: 1.3
  body-lg:
    fontFamily: "'Inter', sans-serif"
    fontSize: 18px
    fontWeight: 400
    lineHeight: 1.5
  body-md:
    fontFamily: "'Inter', sans-serif"
    fontSize: 16px
    fontWeight: 400
    lineHeight: 1.5
  body-sm:
    fontFamily: "'Inter', sans-serif"
    fontSize: 14px
    fontWeight: 400
    lineHeight: 1.5
  label-md:
    fontFamily: "'Inter', sans-serif"
    fontSize: 14px
    fontWeight: 500
    lineHeight: 1.4
    letterSpacing: "0.02em"
  label-sm:
    fontFamily: "'Inter', sans-serif"
    fontSize: 12px
    fontWeight: 500
    lineHeight: 1.4
    letterSpacing: "0.02em"

spacing:
  xs: 8px
  sm: 16px
  md: 24px
  lg: 32px
  xl: 48px
  "2xl": 64px
  "3xl": 96px
  "4xl": 128px
  "5xl": 160px

rounded:
  sm: 0px
  md: 0px
  lg: 2px
  xl: 2px
  full: 9999px

components:
  button-primary:
    backgroundColor: "{colors.primary}"
    textColor: "{colors.surface-container}"
    rounded: "{rounded.full}"
    padding: 16px
    typography: "{typography.label-md}"
  button-primary-hover:
    backgroundColor: "{colors.primary}"
    textColor: "{colors.surface-container}"
  button-secondary:
    backgroundColor: "{colors.secondary}"
    textColor: "{colors.surface-container}"
    rounded: "{rounded.full}"
    padding: 16px
    typography: "{typography.label-md}"
  button-tertiary:
    backgroundColor: "{colors.surface-container}"
    textColor: "{colors.on-surface-variant}"
    rounded: "{rounded.full}"
    padding: 16px
    typography: "{typography.label-md}"
  text-disabled:
    textColor: "{colors.neutral}"
    typography: "{typography.body-sm}"
  button-error:
    backgroundColor: "{colors.error}"
    textColor: "{colors.surface-container}"
    rounded: "{rounded.full}"
    padding: 16px
    typography: "{typography.label-md}"
  input:
    backgroundColor: "{colors.surface}"
    textColor: "{colors.on-surface}"
    rounded: "{rounded.md}"
    padding: 12px
    typography: "{typography.body-md}"
  card:
    backgroundColor: "{colors.surface}"
    textColor: "{colors.on-surface}"
    rounded: "{rounded.md}"
    padding: 32px
  divider:
    backgroundColor: "{colors.outline}"
    height: 1px
---

# GOV.UK

GOV.UK's citizen-service reading — pure-white canvas, gov.uk link blue #1d70b8 as primary, GDS "Start now" green #00703c as success- secondary, deep near-black #0b0c0c ink at WCAG-AAA contrast. The public-service register: constraint-driven layout, accessibility- first chrome, near-zero radii (the famous focus-ring is a literal yellow box, not a curve). Lexend stands in for GDS Transport at the rendering level — both typefaces optimize for reading proficiency above editorial flourish. Distinguished from peer institutional brands (bmw-institutional-light / stripe-modern- light / visa-cardface-light) by typographic register (accessibility-optimized Lexend vs corporate grotesque) and by chrome (zero-radii civic vs modern-rounded SaaS).

This document describes the **Public Service Edition** atmosphere (`gov-uk-citizen-light`) — a light/flat reading of GOV.UK produced by the Void Energy design system. Render it live at https://voidenergy.dev/atmospheres/gov-uk, or boot it in any Void Energy app:

```js
voidEngine.loadExternal('https://voidenergy.dev/atmospheres/gov-uk/citizen-light.json');
```

## Overview

GOV.UK's **Public Service Edition** reading. The mood: opaque surfaces with crisp shadows; the mode: light. Headings are set in Lexend; body copy is Lexend.

Two principles govern everything below:

1. **Generous whitespace over dense packing.** Surfaces breathe. When a gap feels tight, go one size up rather than down. Void Energy's spacing scale is intentionally wide (8 → 160px).
2. **Sentence case controls over uppercase shouting.** Buttons, inputs, and labels use natural sentence case with medium weight by default. Uppercase is an intentional, infrequent choice — never applied to metrics, chrome, or dashboard cards by default.

## Colors

The palette is built on three layers:

- **Primary (`#1d70b8`)** — the single interactive accent. Used for buttons, links, focused inputs, and selection states. Do not repurpose for decoration.
- **Secondary (`#00703c`)** — companion accent for secondary actions, charts, and data-series 2. Always distinguishable from primary; never a competing focal point.
- **Surface stack** — three background layers that convey depth:
  - `surface-container` (`#ffffff`) — the page canvas.
  - `surface` (`#ffffff`) — floating cards, panels, and chrome.
  - `outline` (`#C9CACA`) — borders and dividers. Low-contrast by design: borders should whisper structure, not shout.

Text forms a descending-contrast hierarchy:

- `on-surface` (`#0b0c0c`) — primary text. WCAG AA against surface layers.
- `on-surface-variant` (`#505a5f`) — secondary text, captions, metadata.
- `neutral` (`#6f777b`) — disabled states and tertiary hints only.

Semantic signal:

- `error` (`#a60000`) — destructive actions and validation failures. Reserved for genuinely negative states; not for warnings or info.

## Typography

This atmosphere pairs **Lexend** for headings and **Lexend** for body. The full nine-level scale (display through label) is in the frontmatter `typography` block.

### Runtime font loading

The Void Energy runtime self-loads GOV.UK's typeface family via `new FontFace()` and `document.fonts.add()`. To replicate without the runtime, register the font with your own `@font-face` declaration using:

- **Heading**: `Lexend` — `https://cdn.jsdelivr.net/fontsource/fonts/lexend:vf@latest/latin-wght-normal.woff2` (weight `100 900`)

### Brand typography overrides

GOV.UK's identity carries explicit overrides on the typographic axis. Anything not listed inherits the system default.

- **Display weight** (h1, h2): `700`
- **Heading weight** (h3, h4): `700`
- **Heading tracking** (h3, h4): `0`
- **Body tracking**: `0`

## Layout & Spacing

Void Energy uses an **8px base grid** with a wide scale:

- **Component level** (tight): xs (8), sm (16), md (24), lg (32)
- **Layout level** (accelerated): xl (48), 2xl (64), 3xl (96), 4xl (128), 5xl (160)

Apply along two axes:

1. **Surface padding floor.** Floating surfaces use `lg` (32px) minimum padding and `lg` inner gaps. Sunk/inset surfaces drop to `md` (24px). Never use `sm` or `xs` on a floating card.
2. **Layout gaps.** Page sections use `2xl` (64px) between them. Content blocks inside a section use `xl` (48px). Grouped controls use `md` (24px). Tight couplings (label → input, icon + text) use `xs` (8px).

The scale density-scales at runtime across five presets: Compact (×0.8), Cozy (×0.9), Standard (×1), Roomy (×1.1), Airy (×1.2). Static snapshots assume Standard.

## Elevation & Depth

This is a **flat-physics** atmosphere. Surfaces are opaque (`#ffffff`); shadows are minimal (5–10% opacity in light mode, 30–40% in dark mode for visibility). Hover has no Y translation and no scale by default — flat physics expresses interactivity through tint changes, not lift.

## Shapes

GOV.UK's radii reflect the brand's shape language. The active scale:

- `rounded.sm`: 0px
- `rounded.md`: 0px
- `rounded.lg`: 2px
- `rounded.xl`: 2px
- `rounded.full`: 9999px

## Components

The frontmatter `components` block covers the canonical atoms. Notes on applying them:

### Buttons

- `button-primary` — primary action, anchored on `#1d70b8`. One per view.
- `button-secondary` — companion action, on `#00703c`.
- `button-tertiary` — quietest button; for cancel, dismiss, tertiary navigation.

### Inputs & Cards

- `input` — surface background, `body-md` typography, 12px padding. Native `<input>` / `<select>` / `<textarea>` with SCSS providing the visual treatment.
- `card` — surface background, generous 32px padding (`lg`). The default container for content groups.

## Do's and Don'ts

**Do:**

- Use `primary` (`#1d70b8`) for exactly one action per view.
- Default to sentence case on buttons and labels. Uppercase is a choice, not a default.
- Maintain WCAG AA contrast (4.5:1 for body text, 3:1 for UI components).
- Apply `lg` (32px) padding minimum to cards.
- Wrap native `<button>`, `<input>`, `<select>` rather than rebuilding interaction from `<div>`.

**Don't:**

- Don't substitute the canvas with anything off-white — gov.uk's documented chrome uses pure #ffffff per WCAG-AAA contrast guidance; warm-near-white belongs to NYT/Aesop editorial territory.
- Don't promote the iconic focus-yellow #ffdd00 to energy-secondary — pure yellow fails 3:1 against white and would shatter chart-series contrast across the chrome. Yellow lives only on focus-ring backdrop in the canonical gov.uk system.
- Don't drop Lexend for Inter — Lexend's reading-proficiency design is the closest free analog to GDS Transport's accessibility-first ethos; Inter reads as generic SaaS chrome and loses the civic-service identity.
- Don't repurpose `primary` (`#1d70b8`) for decoration. It is a load-bearing interaction signal.
- Don't use `error` (`#a60000`) for warnings. Error is reserved for destructive and failure states.
- Don't use `neutral` for body text — it is for disabled states and tertiary hints only.

## Responsive Behavior

Void Energy is mobile-first. Breakpoints:

- **mobile** 0px (default)
- **tablet** 768px
- **desktop** 1024px

Spacing, control heights, and typography all density-scale at runtime. Touch targets have a floor: 44px on coarse pointers (mobile/tablet), 36px on fine pointers (desktop).

## Agent Prompt Guide

When asked to build UI "in the Public Service Edition aesthetic," default to:

- **Backgrounds:** `#ffffff` for the page canvas; `#ffffff` for floating cards.
- **Text:** `#0b0c0c` for primary, `#505a5f` for secondary.
- **Accents:** `#1d70b8` for the single most important action; `#00703c` for companion actions.
- **Radii:** 0px on surfaces and inputs; pill on buttons.
- **Padding:** 32px on cards, 16px on buttons, 12px on inputs.
- **Typography:** Lexend for headings; Lexend for body and labels.

## Sources

The Public Service Edition palette and shape language derive from publicly visible GOV.UK surfaces:

- https://design-system.service.gov.uk
- https://design-system.service.gov.uk/styles/colour/
- https://www.gov.uk

## License

Void Energy ships under the Business Source License (BSL 1.1). Source is visible; production use requires a license from DGRS Labs until the four-year auto-convert clause elapses. This DESIGN.md file itself is distributed under the same license as the repository it lives in.

This atmosphere is an atmospheric study of publicly visible GOV.UK design language. Void Energy is not affiliated with, endorsed by, sponsored by, or licensed by GOV.UK. The atmosphere file contains color, motion, and typographic-rhythm tokens only — no brand logos, marks, or proprietary assets.

## The Full System

This file describes the **Public Service Edition** atmosphere as a single snapshot. The Void Energy runtime is larger:

- **GOV.UK variants** — see https://voidenergy.dev/atmospheres/gov-uk for the full set of atmospheres in this brand (alternate modes, eras, or interpretations).
- **Three physics presets:** glass (translucent + blur), flat (opaque + crisp shadows), retro (CRT phosphor + steps motion). Physics controls blur, border width, motion, and radius behavior — never color.
- **Two color modes:** light and dark. Glass requires dark; flat and retro work with both.
- **Density scaling:** Compact / Cozy / Standard / Roomy / Airy (×0.8 – ×1.2), applied multiplicatively to the spacing scale.
- **Component library:** Svelte 5 components (Runes) with a native-first pattern — wrappers around `<button>`, `<input>`, `<select>`, `<dialog>`, etc.
- **JSON download:** https://voidenergy.dev/atmospheres/gov-uk/citizen-light.json is a portable artifact. Boot it in any Void Energy app via `voidEngine.loadExternal()`, or hand it to any tool that consumes the @void-energy/atmosphere-spec format.

For the full installable system, see the Void Energy repository. For agent-to-agent communication outside the live runtime, this DESIGN.md is the authoritative snapshot of the GOV.UK Public Service Edition aesthetic.