Use tomorrow's CSS syntax, today. Via Brunch.

Issues with the output should be reported on cssnext issue tracker.

$ npm install cssnext-brunch

Add a cssnext section in the plugins section of your brunch config file

plugins:
    cssnext:
      sourcemap: true
      features:
        prefixes:
          browsers:['> 5%', 'last 3 version', 'IE 8']
      import:
        path: 'app/css'

Options are directly passed to cssnext, so checkout cssnext options directly.

cssnext-brunch is a compile-type plugin, so it's play well optimizer like clean-css-brunch

For now, sourcemap is inlined in the generated css. If you want to enable cssnext sourcemap, you should disabled brunch default sourcemap.

Also, it seems that minification (via compress option or via another brunch plugin) broke sourcemap support.

By default, brunch concatenates css files. In order to take advantage of postcss-import, you'll need to add _ to filename (* @import "_filename.css"*. You also need to specify import folder in the brunch config. import: "app/css" for example.

When build for production, inlined sourcemap is disabled.