Repository: storybook
Issue: [Bug]: 3rd Party Global Styles not loading
Labels: bug,compatibility with other tools,nextjs,sev:S3,addon: themes

### Describe the bug

Importing a 3rd party CSS file _(CSS file in `node_modules`)_ into the `.storybook/preview.tsx` file does not result in that CSS being loaded into the preview iframe.

### To Reproduce

Reproduction repository: https://github.com/halcarleton/storybook-radix-issue

This is a bare bones NextJS app created with:

```
npx create-next-app@latest
npx storybook@latest init
```
Then Radix theme is installed and integrated into both the Next app and the Storybook preview.

---

Steps to repro: 

1. `npm install`
1. `npm run dev`
1. Open the running app at the localhost port provided in the output of the above command.
1. Confirm that there are two styled elements visible on the page:
   * a blue button using the Radix theme
   * a pink div styled with a global CSS file
1. `npm run storybook`
1. Open the Example/Button/Primary story
1. See that the Radix Theme styling is not applied
1. Open the Example/TestElement/Primary story
1. See that the test element is styled according to the global CSS

Additional debugging steps:

1. Copy the content of Radix Theme's `styles.css` file and paste it into the project's `./src/app/globals.css` file.
1. `npm run storybook`
1. Notice that the Example/Button/Primary story now contains the correct styling.

This suggests that the issue is not with the imported CSS file, but instead seems to be specific to importing from `node_modules`.

---

For quick reference, this is the content of the `.storybook/preview.tsx` file:

This is the base content initialized by the `storybook init` command. The updated pieces are:

* importing the Radix Theme global CSS file
* Importing the project's global CSS file
* Adding a decorator to wrap the preview in the Theme element(necessary for applying radix theme styling)

```tsx
import React from 'react';
import type { Preview } from "@storybook/react";
import { Theme } from "@radix-ui/themes";
import '@radix-ui/themes/styles.css';
import '../src/app/globals.css'

const preview: Preview = {
  decorators: [
    (Story) => (<Theme><Story /></Theme>),
  ],
  parameters: {
    actions: { argTypesRegex: "^on[A-Z].*" },
    controls: {
      matchers: {
        color: /(background|color)$/i,
        date: /Date$/i,
      },
    },
  },
};

export default preview;

```

### System

```bash
Storybook Environment Info:

  System:
    OS: macOS 11.7.6
    CPU: (12) x64 Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 20.9.0 - ~/.nvm/versions/node/v20.9.0/bin/node
    npm: 10.2.2 - ~/.nvm/versions/node/v20.9.0/bin/npm <----- active
  Browsers:
    Chrome: 120.0.6099.109
    Safari: 16.2
  npmPackages:
    @storybook/addon-essentials: ^7.6.4 => 7.6.4
    @storybook/addon-interactions: ^7.6.4 => 7.6.4
    @storybook/addon-links: ^7.6.4 => 7.6.4
    @storybook/addon-onboarding: ^1.0.10 => 1.0.10
    @storybook/blocks: ^7.6.4 => 7.6.4
    @storybook/nextjs: ^7.6.4 => 7.6.4
    @storybook/react: ^7.6.4 => 7.6.4
    @storybook/test: ^7.6.4 => 7.6.4
    eslint-plugin-storybook: ^0.6.15 => 0.6.15
    storybook: ^7.6.4 => 7.6.4
```
```


### Additional context

_No response_