Is there an existing issue for this?

• I have searched the existing issues for a bug report that matches the one I want to file, without success.

Did you read the documentation and troubleshoot guide?

• I have read the documentation and troubleshoot guide

Environment

web

Steps To Reproduce

1. View https://doc.sagemath.org/html/en/thematic_tutorials/lie/crystals.html#crystals-of-letters
2. Switch the doc theme to dark mode.

Expected Behavior

Crystals should glow in the dark.

Actual Behavior

Crystals cannot be seen.

Additional Information

@anneschilling @tscrim