PostCSS

Setup

Follow the steps below to transform CSS using any of the available PostCSS plugins.

Step 1

Install Node.js.

Step 2

Install the required Node.js packages in the root of your project. For example, to add vendor prefixes to CSS rules:

npm install postcss postcss-cli autoprefixer

Step 3

Create a PostCSS configuration file in the root of your project. You must name this file postcss.config.js or one of the other supported file names. For example:

module.exports = {
  plugins: [
    require('autoprefixer')
  ]
};

Step 4

Place your CSS file within the assets directory.

Step 5

Capture the CSS file as a resource and pipe it through resources.PostCSS (alias postCSS):

{{ with resources.Get "css/main.css" | postCSS }}
  <link rel="stylesheet" href="{{ .RelPermalink }}">
{{ end }}

If starting with a Sass file within the assets directory:

{{ with resources.Get "sass/main.scss" | toCSS | postCSS }}
  <link rel="stylesheet" href="{{ .RelPermalink }}">
{{ end }}

Options

The resources.PostCSS method takes an optional map of options.

config

(string) The directory that contains the PostCSS configuration file. Default is the root of the project directory.

noMap

(bool) Default is false. If true, disables inline sourcemaps.

inlineImports

(bool) Default is false. Enable inlining of @import statements. It does so recursively, but will only import a file once. URL imports (e.g. @import url('https://fonts.googleapis.com/css?family=Open+Sans&display=swap');) and imports with media queries will be ignored. Note that this import routine does not care about the CSS spec, so you can have @import anywhere in the file. Hugo will look for imports relative to the module mount and will respect theme overrides.

skipInlineImportsNotFound New in v0.99.0

(bool) Default is false. Before Hugo 0.99.0 when inlineImports was enabled and we failed to resolve an import, we logged it as a warning. We now fail the build. If you have regular CSS imports in your CSS that you want to preserve, you can either use imports with URL or media queries (Hugo does not try to resolve those) or set skipInlineImportsNotFound to true.

{{ $opts := dict "config" "config-directory" "noMap" true }}
{{ with resources.Get "css/main.css" | postCSS $opts }}
  <link rel="stylesheet" href="{{ .RelPermalink }}">
{{ end }}

No configuration file

To avoid using a PostCSS configuration file, you can specify a minimal configuration using the options map.

use

(string) A space-delimited list of PostCSS plugins to use.

parser

(string) A custom PostCSS parser.

stringifier

(string) A custom PostCSS stringifier.

syntax

(string) Custom postcss syntax.

{{ $opts := dict "use" "autoprefixer postcss-color-alpha" }}
{{ with resources.Get "css/main.css" | postCSS $opts }}
  <link rel="stylesheet" href="{{ .RelPermalink }}">
{{ end }}

Check Hugo environment

The current Hugo environment name (set by --environment or in config or OS environment) is available in the Node context, which allows constructs like this:

module.exports = {
  plugins: [
    require('autoprefixer'),
    ...process.env.HUGO_ENVIRONMENT === 'production'
      ? [purgecss]
      : []
  ]
}