Accessing the current mode (Dark/Light)

[ArieLevental]

How can I access the current mode via JavaScript?
I'm using NextJS+Tailwind+shadcn, and I'm trying to style an element using a CSS file.
I don't know how to conditionally style for different modes, and thought about 2 possible ways:

1. Accessing global CSS variables in the CSS file
2. Accessing current mode and conditionally rendering class names.
   First options sounds much cleaner if it's an option.

Sorry for the newbie question, first time using those technologies.
Thanks a lot!