PostCSS

PostCSS is a tool for transforming styles with JS plugins.
These plugins can lint your CSS, support variables and mixins,
transpile future CSS syntax, inline images, and more.

PostCSS is used by industry leaders including Wikipedia, Twitter, Alibaba,
and JetBrains. The [Autoprefixer] and [Stylelint] PostCSS plugins are some of the most popular CSS tools.

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Built by
Evil Martians, go-to agency for developer tools.

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[Abstract Syntax Tree]: https://en.wikipedia.org/wiki/Abstract_syntax_tree
[Evil Martians]: https://evilmartians.com/?utm_source=postcss
[Autoprefixer]: https://github.com/postcss/autoprefixer
[Stylelint]: https://stylelint.io/
[plugins]: https://github.com/postcss/postcss#plugins

Sponsorship

PostCSS needs your support. We are accepting donations
at Open Collective.

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Plugins

PostCSS takes a CSS file and provides an API to analyze and modify its rules
(by transforming them into an [Abstract Syntax Tree]).
This API can then be used by [plugins] to do a lot of useful things,
e.g., to find errors automatically, or to insert vendor prefixes.

Currently, PostCSS has more than 200 plugins. You can find all of the plugins
in the [plugins list]. Below is a list of our favorite plugins —
the best demonstrations of what can be built on top of PostCSS.

If you have any new ideas, [PostCSS plugin development] is really easy.

[plugins list]: https://github.com/postcss/postcss/blob/main/docs/plugins.md

Solve Global CSS Problem

• [postcss-use] allows you to explicitly set PostCSS plugins within CSS

• [postcss-modules] and [react-css-modules] automatically isolate

• [postcss-autoreset] is an alternative to using a global reset

• [postcss-initial] adds all: initial support, which resets

• [cq-prolyfill] adds container query support, allowing styles that respond

Use Future CSS, Today

• [autoprefixer] adds vendor prefixes, using data from Can I Use.
• [postcss-preset-env] allows you to use future CSS features today.

Better CSS Readability

• [postcss-nested] unwraps nested rules the way Sass does.
• [postcss-sorting] sorts the content of rules and at-rules.
• [postcss-utilities] includes the most commonly used shortcuts and helpers.
• [short] adds and extends numerous shorthand properties.

Images and Fonts

• [postcss-url] postcss plugin to rebase url(), inline or copy asset.
• [postcss-sprites] generates image sprites.
• [font-magician] generates all the @font-face rules needed in CSS.
• [postcss-inline-svg] allows you to inline SVG and customize its styles.
• [postcss-write-svg] allows you to write simple SVG directly in your CSS.
• [webp-in-css] to use WebP image format in CSS background.
• [avif-in-css] to use AVIF image format in CSS background.

Linters

• [stylelint] is a modular stylesheet linter.
• [stylefmt] is a tool that automatically formats CSS

• [doiuse] lints CSS for browser support, using data from Can I Use.
• [colorguard] helps you maintain a consistent color palette.

Other

• [cssnano] is a modular CSS minifier.
• [lost] is a feature-rich calc() grid system.
• [rtlcss] mirrors styles for right-to-left locales.

Syntaxes

PostCSS can transform styles in any syntax, not just CSS.
If there is not yet support for your favorite syntax,
you can write a parser and/or stringifier to extend PostCSS.

• [sugarss] is a indent-based syntax like Sass or Stylus.
• [postcss-syntax] switch syntax automatically by file extensions.
• [postcss-html] parsing styles in ` tags of HTML-like files.
• [postcss-markdown] parsing styles in code blocks of Markdown files.
• [postcss-styled-syntax] parses styles in template literals CSS-in-JS

• [postcss-jsx] parsing CSS in template / object literals of source files.
• [postcss-styled] parsing CSS in template literals of source files.
• [postcss-scss] allows you to work with SCSS

• [postcss-sass] allows you to work with Sass

• [postcss-less] allows you to work with Less

• [postcss-less-engine] allows you to work with Less

• [postcss-js] allows you to write styles in JS or transform

• [postcss-safe-parser] finds and fixes CSS syntax errors.
• [midas] converts a CSS string to highlighted HTML.

The best way to use PostCSS with CSS-in-JS is [astroturf].
Add its loader to your webpack.config.js:

js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: ['style-loader', 'postcss-loader']
      },
      {
        test: /\.jsx?$/,
        use: ['babel-loader', 'astroturf/loader']
      }
    ]
  }
}

Then create postcss.config.js:

js
/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

[astroturf]: https://github.com/4Catalyzer/astroturf

[Parcel] has built-in PostCSS support. It already uses Autoprefixer
and cssnano. If you want to change plugins, create postcss.config.js
in project’s root:

js
/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

Use [postcss-loader] in webpack.config.js:

js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        exclude: /node_modules/,
        use: [
          {
            loader: 'style-loader'
          },
          {
            loader: 'css-loader',
            options: {
              importLoaders: 1
            }
          },
          {
            loader: 'postcss-loader'
          }
        ]
      }
    ]
  }
}

Then create postcss.config.js:

js
/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

[postcss-loader]: https://github.com/postcss/postcss-loader

Use [gulp-postcss] and [gulp-sourcemaps].

js
gulp.task('css', () => {
  const postcss = require('gulp-postcss')
  const sourcemaps = require('gulp-sourcemaps')

  return gulp
    .src('src/**/*.css')
    .pipe(sourcemaps.init())
    .pipe(postcss([require('autoprefixer'), require('postcss-nested')]))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('build/'))
})

[gulp-sourcemaps]: https://github.com/floridoo/gulp-sourcemaps
[gulp-postcss]: https://github.com/postcss/gulp-postcss

To use PostCSS from your command-line interface or with npm scripts
there is [postcss-cli].

sh
postcss --use autoprefixer -o main.css css/*.css

[postcss-cli]: https://github.com/postcss/postcss-cli

To apply PostCSS plugins to React Inline Styles, JSS, Radium
and other [CSS-in-JS], you can use [postcss-js] and transforms style objects.

js
const postcss = require('postcss-js')
const prefixer = postcss.sync([require('autoprefixer')])

prefixer({ display: 'flex' }) //=> { display: ['-webkit-box', '-webkit-flex', '-ms-flexbox', 'flex'] }

[postcss-js]: https://github.com/postcss/postcss-js
[Browserify]: https://browserify.org/
[CSS-in-JS]: https://github.com/MicheleBertoli/css-in-js
[webpack]: https://webpack.github.io/

• Grunt: @lodder/grunt-postcss
• HTML: posthtml-postcss
• Stylus: poststylus
• Rollup: rollup-plugin-postcss
• Brunch: postcss-brunch
• Broccoli: broccoli-postcss
• Meteor: postcss
• ENB: enb-postcss
• Taskr: taskr-postcss
• Start: start-postcss
• Connect/Express: postcss-middleware
• Svelte Preprocessor: svelte-preprocess

js
const autoprefixer = require('autoprefixer')
const postcss = require('postcss')
const postcssNested = require('postcss-nested')
const fs = require('fs')

fs.readFile('src/app.css', (err, css) => {
  postcss([autoprefixer, postcssNested])
    .process(css, { from: 'src/app.css', to: 'dest/app.css' })
    .then(result => {
      fs.writeFile('dest/app.css', result.css, () => true)
      if (result.map) {
        fs.writeFile('dest/app.css.map', result.map.toString(), () => true)
      }
    })
})

• syntax: an object providing a syntax parser and a stringifier.
• parser: a special syntax parser (for example, [SCSS]).
• stringifier: a special syntax output generator (for example, [Midas]).
• map: [source map options].
• from: the input file name (most runners set it automatically).
• to`: the output file name (most runners set it automatically).

Treat Warnings as Errors

In some situations it might be helpful to fail the build on any warning
from PostCSS or one of its plugins. This guarantees that no warnings
go unnoticed, and helps to avoid bugs. While there is no option to enable
treating warnings as errors, it can easily be done

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