273 lines
5.7 KiB
Markdown
273 lines
5.7 KiB
Markdown
# PostCSS Extend Rule [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS Logo" width="90" height="90" align="right">][postcss]
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[![NPM Version][npm-img]][npm-url]
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[![Build Status][cli-img]][cli-url]
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[![Support Chat][git-img]][git-url]
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[PostCSS Extend Rule] lets you use the `@extend` at-rule and
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[Functional Selectors] in CSS, following the speculative
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[CSS Extend Rules Specification].
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```pcss
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%thick-border {
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border: thick dotted red;
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}
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.serious-modal {
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font-style: normal;
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font-weight: bold;
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@media (max-width: 240px) {
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@extend .modal:hover;
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}
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}
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.modal {
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@extend %thick-border;
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color: red;
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}
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.modal:hover:not(:focus) {
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outline: none;
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}
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/* becomes */
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.serious-modal {
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font-style: normal;
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font-weight: bold;
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}
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@media (max-width: 240px) {
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.serious-modal:not(:focus) {
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outline: none;
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}
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}
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.modal {
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border: thick dotted red;
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color: red;
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}
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.modal:hover:not(:focus) {
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outline: none;
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}
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```
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## Usage
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Add [PostCSS Extend Rule] to your build tool:
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```bash
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npm install postcss-extend-rule --save-dev
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```
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#### Node
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Use [PostCSS Extend Rule] to process your CSS:
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```js
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import postcssExtend from 'postcss-extend-rule';
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postcssExtend.process(YOUR_CSS, /* processOptions */ /*, pluginOptions */);
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```
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#### PostCSS
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Add [PostCSS] to your build tool:
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```bash
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npm install postcss --save-dev
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```
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Use [PostCSS Extend Rule] as a plugin:
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```js
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import postcss from 'gulp-postcss';
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import postcssExtend from 'postcss-extend-rule';
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postcss([
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postcssExtend(/* pluginOptions */)
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]).process(YOUR_CSS);
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```
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#### Webpack
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Add [PostCSS Loader] to your build tool:
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```bash
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npm install postcss-loader --save-dev
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```
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Use [PostCSS Extend Rule] in your Webpack configuration:
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```js
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import postcssExtend from 'postcss-extend-rule';
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module.exports = {
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module: {
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rules: [
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{
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test: /\.css$/,
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use: [
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'style-loader',
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{ loader: 'css-loader', options: { importLoaders: 1 } },
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{ loader: 'postcss-loader', options: {
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ident: 'postcss',
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plugins: () => [
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postcssExtend(/* pluginOptions */)
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]
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} }
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]
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}
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]
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}
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}
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```
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#### Gulp
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Add [Gulp PostCSS] to your build tool:
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```bash
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npm install gulp-postcss --save-dev
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```
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Use [PostCSS Extend Rule] in your Gulpfile:
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```js
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import postcss from 'gulp-postcss';
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import postcssExtend from 'postcss-extend-rule';
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gulp.task('css', () => gulp.src('./src/*.css').pipe(
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postcss([
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postcssExtend(/* pluginOptions */)
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])
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).pipe(
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gulp.dest('.')
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));
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```
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#### Grunt
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Add [Grunt PostCSS] to your build tool:
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```bash
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npm install grunt-postcss --save-dev
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```
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Use [PostCSS Extend Rule] in your Gruntfile:
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```js
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import postcssExtend from 'postcss-extend-rule';
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grunt.loadNpmTasks('grunt-postcss');
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grunt.initConfig({
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postcss: {
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options: {
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use: [
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postcssExtend(/* pluginOptions */)
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]
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},
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dist: {
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src: '*.css'
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}
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}
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});
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```
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## Options
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### name
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The `name` option determines the at-rule name being used to extend selectors.
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By default, this name is `extend`, meaning `@extend` rules are parsed.
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```js
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postcssExtend({ name: 'postcss-extend' })
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```
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If the `name` option were changed to, say, `postcss-extend`, then only
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`@postcss-extend` at-rules would be parsed.
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```pcss
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main {
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@postcss-extend .some-rule;
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}
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```
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### onFunctionalSelector
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The `onFunctionalSelector` option determines how functional selectors should be
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handled. Its options are:
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- `remove` (default) removes any functional selector
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- `ignore` ignores any functional selector and moves on
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- `warn` warns the user whenever it encounters a functional selector
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- `throw` throws an error if ever it encounters a functional selector
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```js
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postcssExtend({ onFunctionalSelector: 'remove' /* default */ })
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```
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```pcss
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%this-will-be-removed {}
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```
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### onRecursiveExtend
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The `onRecursiveExtend` option determines how recursive extend at-rules should
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be handled. Its options are:
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- `remove` (default) removes any recursive extend at-rules
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- `ignore` ignores any recursive extend at-rules and moves on
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- `warn` warns the user whenever it encounters a recursive extend at-rules
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- `throw` throws an error if ever it encounters a recursive extend at-rules
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```js
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postcssExtend({ onRecursiveExtend: 'remove' /* default */ })
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```
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```pcss
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.this-will-not-extend-itself {
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@extend .this-will-not-extend-itself;
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}
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```
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### onUnusedExtend
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The `onUnusedExtend` option determines how an unused extend at-rule should be
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handled. Its options are:
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- `remove` (default) removes any unused extend at-rule
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- `ignore` ignores any unused extend at-rule and moves on
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- `warn` warns the user whenever it encounters an unused extend at-rule
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- `throw` throws an error if ever it encounters an unused extend at-rule
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```js
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postcssExtend({ onUnusedExtend: 'remove' /* default */ })
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```
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```pcss
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main {
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@extend .this-selector-does-not-exist-and-will-be-removed;
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}
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```
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[cli-img]: https://img.shields.io/travis/jonathantneal/postcss-extend-rule.svg
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[cli-url]: https://travis-ci.org/jonathantneal/postcss-extend-rule
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[git-img]: https://img.shields.io/badge/support-chat-blue.svg
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[git-url]: https://gitter.im/postcss/postcss
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[npm-img]: https://img.shields.io/npm/v/postcss-extend-rule.svg
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[npm-url]: https://www.npmjs.com/package/postcss-extend-rule
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[CSS Extend Rules Specification]: https://jonathantneal.github.io/specs/css-extend-rule/
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[Functional Selectors]: https://jonathantneal.github.io/specs/css-extend-rule/#functional-selector
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[Gulp PostCSS]: https://github.com/postcss/gulp-postcss
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[Grunt PostCSS]: https://github.com/nDmitry/grunt-postcss
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[PostCSS]: https://github.com/postcss/postcss
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[PostCSS Loader]: https://github.com/postcss/postcss-loader
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[PostCSS Extend Rule]: https://github.com/jonathantneal/postcss-extend-rule
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