# One UI (ワンUI)

> Samsung's design language for Galaxy devices. It cuts the screen at the height a thumb reaches most easily and calls the part above that the viewing area and the part below the interaction area, so titles sit high while buttons, tabs and dialogs are gathered low. Content is collected into containers with heavily rounded corners, the ground is either white or true black, and a single blue carries every accent.

- IndexStyle No.522 — https://indexstyle.org/styles/one-ui
- Kind: Style · Family: Platform Screen Languages · Era: 2018–
- Mood: Calm, Intimacy, Trust
- Color cues: #0381FE / #FAFAFA / #000000 (cues taken from reference works, not a fixed palette)

## Defining characteristics

- The upper part of the screen holds nothing but a title and open space, with no touchable control in it
- Text and images are collected into card shaped containers with strongly rounded corners
- The title bar has only two states, expanded and collapsed, and never rests anywhere in between
- In the dark theme the ground goes to true black and only the blue accent sits on top of it

## Best used for

- Pulling every control to the lower half of a large phone screen so one thumb can reach all of them
- Rebuilding a list screen as a set of rounded containers instead of rows divided by rules

## Composition recipe

- Typography & lettering: Let the title fill the height of the upper area and open a wide gap between it and body text. The collapsed title may be a shorter, different string from the expanded one.
- Layout & structure: Split the screen at thumb reach. Keep only the title and open space above, and move everything that is pressed, switched or confirmed below it. Never let the side margins fall under 24dp.
- Material & texture: Round corners generously, roughly 12dp to 26dp. Choose one of two grounds, #fafafa or #000000, restrict the accent to a single blue, and bring no other hue onto the screen.

## What to avoid

Putting a pressable control into the viewing area destroys the reason for splitting the screen at all, and what is left is just a layout with a lot of empty space at the top.

## Application checklist

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

- [ ] The upper part of the screen holds nothing but a title and open space, with no touchable control in it
- [ ] Text and images are collected into card shaped containers with strongly rounded corners
- [ ] The title bar has only two states, expanded and collapsed, and never rests anywhere in between
- [ ] In the dark theme the ground goes to true black and only the blue accent sits on top of it
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Material Design (マテリアルデザイン)** — A design system that reduces the physical metaphor of paper and ink to rules of shadow and overlap. Elements are given elevation, shadow states the hierarchy, and motion carries physical cause and effect. It became the model for UI design being distributed as a system. → https://indexstyle.org/styles/material-design
- **Bento Grid (ベントーグリッド)** — Divides different kinds of information into independent boxes, giving the whole picture at a glance. → https://indexstyle.org/styles/bento-grid

## Further study

- One UI Design Guidelines の Structure 章にある領域分割の定義
- 開いた見出しと畳まれた見出しで文言を変えてよいとする規定
- Android のカラーカテゴリの仕組みを One UI がどう流用しているか

## Reference works

- Armen777444《One UI 7 のデバイスケア画面》2025年 — Wikimedia Commons / CC BY 4.0 — https://commons.wikimedia.org/wiki/File:Samsung%20Device%20Care%20One%20UI%207.jpg
- 《One UI 5 のホーム画面》2023年 — Wikimedia Commons / Public domain — https://commons.wikimedia.org/wiki/File:OneUI-5.0-ScreenshotRU.png
- Paowee《Samsung Internet 27 の画面》2024年 — Wikimedia Commons / CC BY-SA 4.0 — https://commons.wikimedia.org/wiki/File:Samsung%20Browser%20Screenshot.png

## Source of record

- Samsung Developer — One UI — https://developer.samsung.com/one-ui

## Machine surfaces

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