v1.0.0-beta261.1Published 2 years ago

CSS Minifier with PostCSS

Meteor CSS Minifier with PostCSS processing.

This package allows you to use PostCSS plugins with .css files. You can add your custom plugins by adding Npm packages using package.json. You can also use your favourite preprocessor side by side with this package.

It allows you to enable many PostCSS plugins, for example Autoprefixer for all preprocessors you use.


  1. Remove standard-minifier-css package

    meteor remove standard-minifier-css
  2. Add minifier-css-postcss package

    meteor add minifier-css-postcss
  3. Add peer NPM dependencies

    meteor npm install -D postcss@8.4.6 postcss-load-config@3.1.1
  4. Add PostCSS plugins:

    You can also install it like npm install -D autoprefixer.

    Then you need to prepare PostCSS configuration under the postcss.plugins.

    Important: Even if you don't want to provide any options you should list your PostCSS plugins in postcss.plugins key. This works that way because order here is important. For example 'postcss-easy-import' should be always first PostCSS plugin on the list and 'autoprefixer' should be the last PostCSS plugin on the list. And devDependencies items can be automatically reordered when installing new by npm install ... -D.

    See example:

    package.json (example):

    2  "name": "demo PostCSS app",
    3  "version": "1.0.0",
    4  "description": "",
    5  "author": "",
    6  "devDependencies": {
    7    "autoprefixer": "^6.5.1",
    8    "mocha": "^3.1.2",
    9    "postcss": "^6.0.22",
    10    "postcss-easy-import": "^1.0.1",
    11    "postcss-load-config": "^1.2.0",
    12    "postcss-nested": "^1.0.0",
    13    "postcss-simple-vars": "^3.0.0",
    14    "rucksack-css": "^0.8.6"
    15  },
    16  "postcss": {
    17    "plugins": {
    18      "postcss-easy-import": {},
    19      "postcss-nested": {},
    20      "postcss-simple-vars": {},
    21      "rucksack-css": {},
    22      "autoprefixer": {"browsers": ["last 2 versions"]}
    23    }
    24  }

    Make sure that the plugins that you list in "plugins" are also in "devDependencies" as well. You may not need the plugins in this example, so please include them only if you need them.

    Remember to run npm install or npm update after changes.

    You can add more plugins here.

    If you want to change something in postcss config later, you should restart your app and also change any .css file to rerun build plugin.

  5. Create your standard .css files with additional features according to PostCSS plugins you use.

PostCSS parsers

You can configure parser for PostCSS. To do this you can add parser key in the package.json file under the postcss key. Let's see an example:

2  "name": "demo PostCSS app",
3  "version": "1.0.0",
4  "description": "",
5  "author": "",
6  "devDependencies": {
7    "autoprefixer": "^6.5.1",
8    "postcss-safe-parser": "^2.0.0"
9  },
10  "postcss": {
11    "plugins": {
12      "autoprefixer": {"browsers": ["last 2 versions"]}
13    },
14    "parser": "postcss-safe-parser"
15  }

As you can see we use here postcss-safe-parser which will repair broken css syntax. This is just one example. You can find a list of parsers here: You can use postcss-scss parser or postcss-less parser.

Exclude Meteor Packages

Because PostCSS processes all CSS files in Meteor, it will also process CSS files from Meteor packages. This is good in most cases and will not break anything, but sometimes it could be problematic.

If you have installed a package which is problematic and PostCSS plugins can't process the CSS files from that package you can exclude it in the process. See for example this issue: #14. In this case you need to exclude constellation:console package because it uses not standard CSS in its files. PostCSS plugin can't process that file. You can exclude it so it will be not processed by PostCSS, but it will be still bundled as is.

If you want to exclude a package you need to use postcss.excludedPackages key, see the example below:

2  "name": "demo PostCSS app",
3  "version": "1.0.0",
4  "description": "",
5  "author": "",
6  "devDependencies": {
7    "autoprefixer": "^6.5.1",
8    "postcss-safe-parser": "^2.0.0"
9  },
10  "postcss": {
11    "plugins": {
12      "autoprefixer": {"browsers": ["last 2 versions"]}
13    },
14    "parser": "postcss-safe-parser",
15    "excludedPackages": ["constellation:console"]
16  }

Remember that you should provide a package name which contains a problematic CSS file and not global wrapper package In this example you want to install babrahams:constellation but in fact the problematic package is constellation:console which is installed with babrahams:constellation. You'll find which package makes troubles by looking into the consolle errors. For example here we have something like:

While minifying app stylesheet:
   packages/constellation_console/client/Constellation.css:118:3: postcss-simple-vars:
   /workspace/meteor/postcss-demo/packages/constellation_console/client/Constellation.css:118:3: Undefined variable $c1

   Css Syntax Error.

   postcss-simple-vars: /workspace/meteor/postcss-demo/packages/constellation_console/client/Constellation.css:118:3: Undefined variable $c1
   background-image: -o-linear-gradient(#000, #000);
   filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='$c1', endColorstr='$c2',GradientType=0);
   color: rgba(255, 255, 255, 0.6);

So we know that this is the problem with constellation:console package.

Imports with PostCSS

You can use imports with postcss-easy-import plugin. Remember that postcss-easy-import plugin should be loaded first (so put it on the first place in the packages.json file under the 'postcss.plugins' key).

You need to use .import.css extension and standard import like with preprocessors @import "my-file.import.css"; Files with .import.css will be ommited by css minifier from this package. You can also put them in an imports folder (from Meteor 1.3). Also read more about postcss-easy-import and postcss-import which is a part of the first one.

Imports from Meteor packages will not work. But there is a good news too. from Meteor 1.3 you can use standard Npm packages and imports from node_modules should work. So you will be able to import css files from instaled Npm packages. You will be able to do something like: @import 'my-npm-lib/styles.css';

Usage with preprocessors like Stylus and Sass

You can use it side by side with your favourite preprocessor. There is an example in the demo app.

You should be able to use PostCSS plugins syntax in the .styl or .scss files too. (Tested only with Stylus).

Tailwind CSS

Tailwind CSS is supported when used with Meteor 2.6.1 or newer.

Since HMR applies updates to js files earlier than the css is updated, there can be a delay when using a Tailwind CSS class the first time before the styles are applied.

Alternative configuration locations

This package uses postcss-load-config to load configuration for PostCSS. This allows you to put PostCSS configuration into alternative locations and not just package.json. An interesting option is to put configuration into .postcssrc.js file in the root directory of your app, which allows you to dynamically decide on the configuration. Example:

1module.exports = (ctx) => {
2  // This flag is set when loading configuration by this package.
3  if (ctx.meteor) {
4    const config = {
5      plugins: {
6        'postcss-easy-import': {},
7      },
8    };
10    if (ctx.env === 'production') {
11      // "autoprefixer" is reported to be slow,
12      // so we use it only in production.
13      config.plugins.autoprefixer = {
14        browsers: [
15          'last 2 versions',
16        ],
17      };
18    }
20    return config;
21  }
22  else {
23    return {};
24  }

Demo test repo

Check out the demo repo. This is the best way of learning.



Also check out


This package was incorporated into core in Meteor 2.6.1 so the changes after the one below are going to appear in Meteor changelog.

The last community maintained version of this package was juliancwirko:postcss.

  • v2.0.7 Update postcss to 8.3.x and postcss-load-config to 3.1.x, other dependencies updated as well.
  • v2.0.6 Update tmeasday:check-npm-versions dep to 1.0.1
  • v2.0.5 Update/fix dependency checks
  • v2.0.3 Restoring the use of app-module-path
  • v2.0.2 Moved to use peer NPM dependencies
  • v2.0.1 Bumping PostCSS to 6.0.22
  • v2.0.0 Started using postcss-load-config for loading configuration
  • v1.3.0 Bumping PostCSS to 6.0.17
  • v1.2.0 Updates (works quite well with Meteor 1.4.2)
  • v1.1.1 Removed fs.existsSync call because of #18
  • v1.1.0 Exclude Meteor package option #14
  • v1.0.0 Version bump for Meteor 1.3
  • v1.0.0-rc.12 Version bump for Meteor 1.3 rc 12
  • v1.0.0-rc.10 Version bump for Meteor 1.3 rc 10
  • v1.0.0-rc.4 Version bump for Meteor 1.3 rc 4
  • v1.0.0-rc.2 Version bump for Meteor 1.3 rc 2
  • v1.0.0-beta.11 Versions bump for Meteor 1.3 beta 11
  • v1.0.0-beta.1 Modifications for Meteor 1.3 beta 4
  • v0.2.5 Removed Promise Polyfill #4
  • v0.2.4 Catch PostCSS 'CssSyntaxError' #3
  • v0.2.3 PostCSS (v5.0.12) version bump
  • v0.2.2 PostCSS (v5.0.11) version bump - performance improvements