Issue with Gear that is supposed to switch theme between light and dark mode

[Hariaksha]

First, thank you for creating this amazing resource. It is really helpful.

Has anyone had any issues with the gear icon at the top? If so, how did you fix it? I describe my issue below.

I saw one discussion post with an answer saying that my issue is that the desired link to the website (Hariaksha.com) is different than the original link "Hariaksha.github.io" so I got rid of the custom domain and it worked correctly again. However, is there a way to keep that functionality on the website while still having a custom domain?

Describe the bug
The gear at the mast head (top) does not do anything when it is clicked on for my code.
Link to my code: https://github.com/Hariaksha/hariaksha.github.io
Link to the website: https://hariaksha.com/

To Reproduce
Click on the gear icon at the top of the website.

Expected behavior
The theme is supposed to switch from light mode to dark mode and vice versa.

Browser (please complete the following information):
Device: MacBook Air M4, 2025
OS: MacOS
Browser: Safari
Version: Tahoe 26.1

Additional context
The problem does not happen on the official Academic Pages site or two other pages that were forked from Academic Pages on my browser and computer, so I do not think that it is a browser or hardware issue. Also, I attached links to my code and the website at the top. I have looked through my commits multiple times to see what edits of mine could have disabled that gear icon to work, but I still have no idea why it is not working. Please let me know if you have a solution to this.