webpack.prod.js

const { merge } = require('webpack-merge');
const common = require('./webpack.common.js');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = merge(common, {
  mode: 'production',
  module: {
    rules: [
      {
        test: /\.(sa|sc|c)ss$/i,
        use: [
          MiniCssExtractPlugin.loader,
          {
            loader: 'css-loader',
            options: { modules: true },
          },
          'postcss-loader',
          'sass-loader',
        ],
      },
    ],
  },
  plugins: [new MiniCssExtractPlugin()],
});