C preprocessor directives not highlighted in Coal/Navy themes

### Problem

You can see this on https://tavianator.com/2023/futex.html for example.  Screenshot:

![Screenshot](https://github.com/user-attachments/assets/7573d855-6e6d-4210-96d5-6c951fb62697)

Ideally the `#include` and `#define` would get a different color than the rest of the text.

### Proposed Solution

_No response_

### Notes

_No response_