Material 3 theme editor

Google's design system: 47 colour roles derived from ONE seed, plus web components. UISandbox builds Material 3 2.5.0 from its own package and opens it in the editor: seven screens in Material 3's own components and its own defaults. Turn the brand, the type, the spacing and the corners, and every component follows. Nothing to install, nothing uploaded.

Open Material 3 in the editor Try it on your own app

Material 3 in the UISandbox editor: the knobs on the left, Material 3's own components on the right — Material 3 as it ships, in the editor. A real screenshot.

What is read from Material 3

Version: 2.5.0
Licence: Apache-2.0
Package: @material/web
Runs in: any page, no framework asked
Variables: 65 in its light mode, and its own dark mode, read from its package
Brand as it ships: #6750a4
Body type: Roboto Flex
Corners: 12px

What you take with you

Export writes Material 3's design system in Material 3's own names, starting from what you see:

theme.css: the variables, in Material 3's own names, as the knobs left them
install.md: where each file goes, step by step
MANIFEST.md: what could not be done, said rather than substituted
DESIGN.md: the design system for people and agents: colours, type, spacing, what each is for
.claude/skills/design-system/SKILL.md: for Claude Code, Cursor or Codex: build the next screen in Material 3's own classes
tokens.json: W3C design tokens, which Tokens Studio and Figma variables import

On your own app

If your app runs on Material 3, the sandbox recognises it from the rendered page and writes the design system in Material 3's names from your app's own values. What you turned on the kit comes with you. The quickest way in is the one where nothing leaves your machine: run npx uisandbox-mcp open in your project, or ask your agent to "open this app in UISandbox". How it works.