Using presets

storybook-preset-babel.js

export const babel = async (base, config) => ({
  rootMode: 'upward',
  sourceType: 'unambiguous',
});

storybook-preset-sass.js

export const webpack = async (base, config) => {
  const { default: webpackMerge } = await import('webpack-merge');

  return webpackMerge(base, {
    module: {
      rules: [{
        test: /.scss/,
        loader: 'sass-loader',
      }],
  });
};