Z-index issue in settings/accordion
## Bug report

### Required System information

- Node.js version: 20
- Strapi version: 5.4.0
- Database: N/A
- Operating system: Mac OS
- Is your project Javascript or Typescript: JS/TS

### Describe the bug
There is a z-index issue with the header and an open accordion, you can easily see this when using the user/permissions plugin. 

### Steps to reproduce the behavior

1. Start a new Strapi project
2. Navigate to any settings section that has an accordion
3. Scroll up

### Expected behavior

The header is always above the content of the page

### Screenshots

![image](https://github.com/user-attachments/assets/9818030a-6f7c-45ca-81b8-8ad9e268ed47)

![image](https://github.com/user-attachments/assets/5b45e8f4-c091-4415-8328-6db4b61c4128)

