Guides

Using Panda in a Component Library

When creating a component library that uses Panda which can be used in a variety of different projects, you have four options:

1. Ship a Panda preset
2. Ship a static CSS file
3. Use Panda as external package, and ship the src files
4. Use Panda as external package, and ship the build info file

Ship a Panda Preset

This is the simplest approach. You can include the token, semantic tokens, text styles, etc. within a preset and consume them in your projects.

Library code

import { definePreset } from '@pandacss/dev'
 
export const acmePreset = definePreset({
  theme: {
    extend: {
      tokens: {
        colors: { primary: { value: 'blue.500' } }
      }
    }
  }
})

Build the preset code

pnpm tsup src/index.ts

App code

import { acmePreset } from '@acme-org/panda-preset'
import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  presets: ['@pandacss/dev/presets', acmePreset]
})

Ship a Static CSS File

This approach involves extracting the static css of your library at build time. Then you can import the CSS file in your app code.

Library code

import { css } from '../styled-system/css'
 
export function Button({ children }) {
  return (
    <button type="button" className={css({ bg: 'red.300', px: '2', py: '3' })}>
      {children}
    </button>
  )
}

Then you can build the library code and generate the static CSS file:

# build the library code
tsup src/index.tsx
 
# generate the static CSS file
panda cssgen --outfile dist/styles.css

Finally, don't forget to include the cascade layers as well in your app code:

App code

import { Button } from '@acme-org/design-system'
import './main.css'
 
export function App() {
  return <Button>Click me</Button>
}

main.css

@layer reset, base, tokens, recipes, utilities;
@import url('@acme-org/design-system/dist/styles.css');
 
/* Your own styles here */

This approach comes with a few downsides:

• You can't customize the styles since the css is already generated

• You might need add the prefix option to avoid className conflicts

  import { defineConfig } from '@pandacss/dev'
   
  export default defineConfig({
    //...
    prefix: 'acme'
  })

• You might have duplicate CSS classes when using multiple atomic css libraries

Use Panda as external package

Include the src files

Library code

Include the src directory of your library in the package.json files field:

{
  "name": "@acme-org/design-system",
  "files": ["src", "dist"]
}

Convert the styled-system directory to a package by setting the emitPackage and outdir properties. This will inform Panda to emit the code artifacts to the node_modules.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

Next, you need to run the panda codegen command. Going forward, you'll now import the functions from the @acme-org/styled-system package.

import { css } from '@acme-org/styled-system/css'
 
export function Button({ children }) {
  return (
    <button type="button" className={css({ bg: 'red.300', px: '2', py: '3' })}>
      {children}
    </button>
  )
}

Mark the @acme-org/styled-system as an external package in your library build tool.

tsup src/index.tsx --external @acme-org/styled-system

App code

Set the emitPackage and outdir properties in your app config file to match the library config file.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

This will inform Panda to emit the code artifacts to the node_modules, and create a symlink for the library code. It will also avoid duplicating the runtime JS code.

Include the src directory from the library code in the panda config.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  include: [
    './node_modules/@acme-org/design-system/src/**/*.tsx',
    './src/**/*.{ts,tsx}'
  ],
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

Ship the build info file

This approach is similar to the previous one, but instead of shipping the source code, you ship the Panda build info file. This will have the exact same end-result as adding the sources files in the include, but it will allow you not to ship the source code.

The build info file is a JSON file that only contains the information about the static extraction result, you still need to ship your app build/dist by yourself. It can be used by Panda to generate CSS classes without the need for parsing the source code.

Convert the styled-system directory to a package by setting the emitPackage and outdir properties. This will inform Panda to emit the code artifacts to the node_modules.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

Next, you need to run the panda codegen command. Going forward, you'll now import the functions from the @acme-org/styled-system package.

import { css } from '@acme-org/styled-system/css'
 
export function Button({ children }) {
  return (
    <button type="button" className={css({ bg: 'red.300', px: '2', py: '3' })}>
      {children}
    </button>
  )
}

Mark the @acme-org/styled-system as an external package in your library build tool.

tsup src/index.tsx --external @acme-org/styled-system

Generate the build info file:

panda ship --outfile dist/panda.buildinfo.json

App code

Set the emitPackage and outdir properties in your app config file to match the library config file.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

This will inform Panda to emit the code artifacts to the node_modules, and create a symlink for the library code. It will avoid duplicating the runtime code.

Next, you need to include the build info file from the library code in the panda config.

import { defineConfig } from '@pandacss/dev'
 
export default defineConfig({
  //...
  include: [
    './node_modules/@acme-org/design-system/dist/panda.buildinfo.json',
    './src/**/*.{ts,tsx}'
  ],
  emitPackage: true,
  outdir: '@acme-org/styled-system'
})

Recommendations

• Library Code shouldn't be published on npm and App code uses Panda, use ship build info approach
• App code might not use Panda, use the static css file approach
• App code lives in an internal monorepo, use the include src files approach
• Library code doesn't ship components but only ships tokens, patterns or recipes, use the ship preset approach

Troubleshooting

• When using tsup or any other build tool for your component library, if you run into a module resolution error that looks similar to ERROR: Could not resolve "../styled-system/xxx". Consider setting the outExtensionin the panda config tojs

• If you use Yarn PnP, you might need to set the nodeLinker: node-modules in the .yarnrc.yml file.