next.config.js

module.exports = {
  webpack: config => {
    config.module.rules.push({
      test: /\.scss$/,
      use: [
        {
          loader: 'emit-file-loader',
          options: {
            name: 'dist/[path][name].[ext]',
          },
        },
        'babel-loader',
        'styled-jsx-css-loader',
      ],
    })

    return config
  },
}