# GOV.UK Design System (GOV.UK デザインシステム)

> The design language the UK government's Government Digital Service publishes and maintains for public services. Everything runs in one undecorated left aligned column set in GDS Transport, and the green button keeps square corners while carrying a darker green band along its bottom edge, dropping by exactly that depth when pressed. Whatever holds keyboard focus turns yellow with a black rule under it.

- IndexStyle No.526 — https://indexstyle.org/styles/govuk-design-system
- Kind: Style · Family: Design Systems · Era: 2012–
- Mood: Trust, Calm, Technology
- Color cues: #0B0C0C / #FFDD00 / #0F7A52 (cues taken from reference works, not a fixed palette)

## Defining characteristics

- One undecorated left aligned column, with almost no boxes and no shadows
- A green button with square corners and a darker green band along its bottom edge, which drops by that exact depth when pressed
- Whatever holds keyboard focus turns yellow with a black rule drawn beneath it
- Type sizes step coarsely through 48, 36, 24, 19 and 16px with nothing in between

## Best used for

- Rebuilding a government or public service form as a single left aligned column asking one question per screen
- Making the current focus position unmistakable for someone operating the service by keyboard alone

## Composition recipe

- Typography & lettering: One sans serif only, in five fixed sizes with nothing in between. Headings are bold and body text sits at 19px.
- Layout & structure: Hold the content to a single narrow column and align every element to one left rule. No multi column layouts and no boxes, because a horizontal rule is the only break between topics.
- Material & texture: Colour is tied to meaning and never used decoratively. Buttons keep a corner radius of zero and gain their thickness from a band of their own darker shade along the bottom edge. The focus state is always yellow ground with a black underline.

## What to avoid

Tidying the look by rounding button corners or thinning the borders on form inputs deletes the two signals this style relies on entirely, the pressable thickness and the position of focus.

## Application checklist

Before calling a piece an application of this style, check it against the defining characteristics:

- [ ] One undecorated left aligned column, with almost no boxes and no shadows
- [ ] A green button with square corners and a darker green band along its bottom edge, which drops by that exact depth when pressed
- [ ] Whatever holds keyboard focus turns yellow with a black rule drawn beneath it
- [ ] Type sizes step coarsely through 48, 36, 24, 19 and 16px with nothing in between
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **DIN 1451 (DIN 1451)** — Engineering lettering laid down as a German industrial standard. Its skeleton can be redrawn with ruler and compass, which unified road signs and factory markings, and the trust that came from having no personality is what designers later came to love. → https://indexstyle.org/styles/din-1451
- **Swiss (スイス・スタイル)** — Puts order front and center and makes the information itself the protagonist. → https://indexstyle.org/styles/swiss

## Further study

- GOV.UK Design System の Styles にある色の使用規則
- govuk-frontend の focused ヘルパーが黄色い地と黒い下線をどう作っているか
- GDS Transport という書体の出自と、なぜ政府サービス向けに限って配られるのか

## Reference works

- GOV.UK のトップページに組まれた GDS Transport 2025年 — Wikimedia Commons / Public domain — https://commons.wikimedia.org/wiki/File:Use%20of%20the%20font%20GDS%20Transport%20on%20the%20gov.uk%20website%20(2025).png

## Source of record

- GOV.UK Design System — Styles（英国政府 Government Digital Service） — https://design-system.service.gov.uk/styles/

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/govuk-design-system
- Image-generation prompt (legally clean): https://indexstyle.org/styles/govuk-design-system/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compose_styles; prompts: image-prompt, apply-style)