vue-loader.conf.js

import * as utils from './utils.js'
import config from '../config/index.js'
const isProduction = process.env.NODE_ENV === 'production'

export default {
  loaders: utils.cssLoaders({
    sourceMap: isProduction
      ? config.build.productionSourceMap
      : config.dev.cssSourceMap,
    extract: isProduction
  }),
}