Dashboard theme toggle with animated switch

What are you most proud of, and what would you do differently next time?

The toggle switch is even better than the design requirement. It's animated.

What challenges did you encounter, and how did you overcome them?

Search about toggling between light theme and dark theme, with css and a small Javascript snippet.

The current solution does not include the use of localStorage for keeping the theme selection.

What specific areas of your project would you like help with?

Wish to better understand how to detect the "system" dark theme preference setting, for the case when using localStorage for saving the theme selection.