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PostCSS Logical Polyfill

Installation

PostCSS Logical Polyfill can be installed using your preferred package manager and integrated into any PostCSS workflow.

Requirements

Section titled “Requirements”
  • Node.js 16.0.0 or later
  • PostCSS 8.0.0 or later

Package Manager Installation

Section titled “Package Manager Installation”

npm

Section titled “npm”
Terminal window
npm install postcss-logical-polyfill --save-dev

pnpm

Section titled “pnpm”
Terminal window
pnpm add -D postcss-logical-polyfill

yarn

Section titled “yarn”
Terminal window
yarn add -D postcss-logical-polyfill

Basic Setup

Section titled “Basic Setup”

After installation, add the plugin to your PostCSS configuration:

postcss.config.js

Section titled “postcss.config.js”
module.exports = {
  plugins: [
    'postcss-logical-polyfill'
    // same as the following witout any options
    // require('postcss-logical-polyfill')()
  ]
}

postcss.config.mjs (ES Modules)

Section titled “postcss.config.mjs (ES Modules)”
import logicalPolyfill from 'postcss-logical-polyfill';


export default {
  plugins: [
    logicalPolyfill()
  ]
};

package.json (PostCSS CLI)

Section titled “package.json (PostCSS CLI)”
{
  "postcss": {
    "plugins": {
      "postcss-logical-polyfill": {}
    }
  }
}

Configuration Options

Section titled “Configuration Options”

You can configure the plugin behavior by passing options:

postcss.config.js
module.exports = {
  plugins: [
    require('postcss-logical-polyfill')({
      // Direction selectors (default shown)
      rtl: { selector: '[dir="rtl"]' },
      ltr: { selector: '[dir="ltr"]' },


      // Output order for unscoped properties
      outputOrder: 'ltr-first'  // or 'rtl-first'
    })
  ]
}

See the Configuration Guide for detailed configuration options.

HTML Setup

Section titled “HTML Setup”

Important: For the generated CSS to work correctly, you must set the dir attribute on your HTML:

<!DOCTYPE html>
<html dir="ltr"> <!-- For left-to-right layouts -->
<head>
  <title>My Website</title>
</head>
<body>
  <!-- Your content -->
</body>
</html>

For right-to-left layouts:

<html dir="rtl"> <!-- For right-to-left layouts -->

Without the dir attribute, the generated [dir="ltr"] and [dir="rtl"] selectors won’t match any elements.

Verification

Section titled “Verification”

To verify the plugin is working correctly, create a simple CSS file with logical properties:

input.css
.test {
  margin-inline: 1rem;
  padding-block: 2rem;
  border-inline-start: 1px solid red;
}

After processing, you should see output like:

output.css
.test {
  margin-left: 1rem;
  margin-right: 1rem;
  padding-top: 2rem;
  padding-bottom: 2rem;
}
[dir="ltr"] .test {
  border-left: 1px solid red;
}
[dir="rtl"] .test {
  border-right: 1px solid red;
}

Troubleshooting

Section titled “Troubleshooting”

If you’re having issues with installation or setup, check the Troubleshooting Guide for common problems and solutions.

Next Steps

Section titled “Next Steps”

Now that you have PostCSS Logical Polyfill installed, check out: