Headers in example `*.menu` file are almost unreadable

When I view https://cooklang.org/docs/use-cases/meal-planning/ in Safari on macOS using a light system theme, the headers in the example `*.menu` file are syntax-highlighted as dark grey on a black background, making them almost unreadable.

Here's what I'm seeing:

<img width="729" height="436" alt="Image" src="https://github.com/user-attachments/assets/b3ba2906-66e6-4a48-8856-160cd3fc40d1" />