Hi FlamingPhoenix35,

Dark mode has already been requested many times, so the Khan Academy team should be already working on it. Search up "dark mode" in the help center.

Eli

Yes, Dark mode has been requested many times.  KA's official answer has been that they are not working on it, but suggest users download one of the free browser extensions, such as Dark Reader.

https://support.khanacademy.org/hc/en-us/community/posts/32992461127309-Dark-Mode 

FlamingPhoenix35,
While I agree with you that dark mode would be helpful, KA claims it would take far too much work, and "it’s unlikely that a native dark mode will be available in the foreseeable future."

I suggest checking out Dark Reader.