The pseudo class ":first-child" is potentially unsafe when doing server-side rendering

Nobody has claimed this yet.

### mapbox-gl-js version

3.20.0

### Browser and version

Chrome 146.0.7680.80

### Context:
Product: ui library
Stack: React, Typescript, Emotion

### Expected behavior

Use `:first-of-type` instead of `:first-child`.

### Actual behavior

The imported `mapbox-gl.css` file causes Emotion to log this error to the console:

`The pseudo-class ":first-child" is potentially unsafe when doing server-side rendering. Try changing it to ":first-of-type".`

The error looks valid. The current version of the mapbox-gl.css file still has that pseudo-selector:
https://github.com/mapbox/mapbox-gl-js/blob/main/src/css/mapbox-gl.css

### Link to the demonstration

[Link to reproduce](https://stackblitz.com/edit/vitejs-vite-2d9vybmp?file=src%2FApp.tsx)

### Steps to trigger the unexpected behavior

1. Navigate the link above
2. Wait for the project to set up
3. Open the DevTools's console
4. Observe a result

Start in src/css/mapbox-gl.css and inspect the :first-child selector reported by Emotion. Reproduce the warning with the linked StackBlitz example, then verify that the selector change removes the console error without affecting the stylesheet behavior.

Written by the indexing model from the issue text.