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Stacks is Stack Overflow’s design system. It includes the resources needed to create consistent, predictable interfaces and workflows that conform to Stack Overflow’s principles, design language, and best practices.

Our documentation is built with Stacks itself, using its immutable, atomic classes and components.

The Stacks website documents:


  • Semantic and accessible component markup
  • Cross-browser compatible Less / CSS
  • An icon library


  • Email templates & components

Stacks documentation can be found at

Table of contents

Using Stacks

Using Stacks is outlined in our usage guidelines.

Migrating from v1 to v2

To migrate from Stacks v1 to v2, see our migration guide.

Building Stacks

To contribute to Stacks documentation or its CSS library, you’ll need to build Stacks locally. View our building guidelines.

Having trouble getting these steps to work? Open an issue with a setup label.

Format Stacks

Format the source code with prettier via running:

npm run format

Linting Stacks

Run all lint suites by running:

npm run lint

Lint the styles (stylelint) by running:

npm run lint:css

Lint the typescript source code (eslint) via running:

npm run lint:ts

Lint the source code format (prettier) via running:

npm run lint:format

Testing Stacks

Run all test suites by running:

npm test

Unit/Component Tests

Unit/Component tests are written with DOM Testing Library. Please follow the library's principles and documentation to write tests.

Stacks uses Web Test Runner and Playwright to run tests in a real browser context.

Execute the unit/component tests suite by running:

npm run test:unit

or if you prefer watch mode run:

npm run test:unit:watch

Visual Regression Tests


This Web Test Runner plugin is used to run visual regression tests. Visual regression tests end with this suffix *.visual.test.ts.

Execute the visual regression tests suite by running:

npm run test:visual

After the first run, if there are failing snapshots, they end up overriding the baseline ones in the filesystem (e.g. /screenshots/<browser>/baseline/<name>.png). We do this for easier comparison of the dif directly in vscode and to make sure only the failing snapshots get regenerated (see this GH discussion that inspired the approach).

We also recommend to install this vscode extension for getting better diffs.

Less Tests

This is an experimental suite to test the generation of CSS from Less files. Less tests end with this suffix *.less.test.ts.

Execute the less tests suite by running:

npm run test:less

Update the css snapshots via:

npm run test:less:update

Releasing a new version of Stacks

Stacks uses Semantic Versioning, is distributed via npm, and publishes release notes on Github. Follow the steps below to release a new version of Stacks.

Bump the version number

npm version [major | minor | patch]

Push the new tag

git push && git push --tags

Create release notes on Github

  1. Visit
  2. Choose your new version from the "Choose a tag" dropdown
  3. Click "Generate release notes"
  4. Cleanup and complete the release notes
    • Prominently mention any breaking changes, if applicable
    • Include a "What's Changed" section in the release notes
    • Mention significant bug fixes
    • Mention new features
    • Mention significant under-the-hood changes that could impact consumers

Ship your newly created version to npm

npm publish

Merge develop into production and push

git checkout production && git merge develop && git push

Push the updated docs site

Head to Netlify, navigate to the Stacks overview, click on "Production deploys", and select "Deploy site" from the "Trigger deploy" dropdown.

Bugs and feature requests

Have a bug or feature request? First search existing or closed issues to make sure the issue hasn’t been noted yet. If not, review our issue guidelines for submitting a bug report or feature request.


If you’d like to contribute to Stacks, please read through our contribution guidelines. Included are directions for opening issues, coding standards, and notes on development.


Code and documentation copyright 2017-2024 Stack Exchange, Inc and released under the MIT License.