docs/snippets/common/storybook-main-using-existing-config.js.mdx
```js
// .storybook/main.js
// your app's webpack.config.js
const custom = require('../webpack.config.js');
module.exports = {
webpackFinal: async (config) => {
return { ...config, module: { ...config.module, rules: custom.module.rules } };
},
};
```