Rollup + rollup-plugin-postcss + babel-plugin-react-css-modules. I wanted to use `styleName` in a library that was using CSS modules but was encountering issues of generated scoped names being mismatched. This got babel and the css loader in-sync.

rollup.config.js

```
import postcss from 'rollup-plugin-postcss';
import genericNames from 'generic-names';

// ...

postcss({
  extract: true,
  modules: {
    // Special scoped name generation function used to sync
    // babel-plugin-postcss-modules with rollup-plugin-postcss.
    generateScopedName: (cssname, filepath) => {
      // Generation logic basically adapted from here:
      // https://github.com/gajus/babel-plugin-react-css-modules/blob/9fcb91f5c3d3b181d0087ab7de999ac2c9c1dd11/src/requireCssModule.js#L103-L109
      const generate = genericNames('[local]__[hash:base64:5]', {
        context: 'src',
      });
      return generate(cssname, filepath);
    },
  },
  sourceMap: true,
}),