Как начать использовать SCSS в *.vue для Rails?

Если указать в файле app/javascript/packs/element.vue
style lang="scss" scoped
то получаю ошибку:

ERROR in ./node_modules/css-loader!./node_modules/vue-loader/lib/style-compiler?{"vue":true,"id":"data-v-d8154932","scoped":true,"hasInlineConfig":false}!./node_modules/postcss-loader/lib!./node_modules/sass-loader/lib/loader.js!./node_modules/vue-loader/lib/selector.js?type=styles&index=0!./app/javascript/packs/element.vue
Module build failed: Error: No PostCSS Config found in: /Users/dmitry/rails/website/app/javascript/packs

В конфиге config/webpack/loaders/vue.js уже указан scss:

module.exports = {
  test: /.vue$/,
  loader: 'vue-loader',
  options: {
    extractCSS: true,
    loaders: {
      js: 'babel-loader',
      file: 'file-loader',
      scss: 'vue-style-loader!css-loader!postcss-loader!sass-loader',
      sass: 'vue-style-loader!css-loader!postcss-loader!sass-loader?indentedSyntax'
    }
  }
}