Automatic light/dark mode based on os/browser settings

[pekvasnovsky]

It is pretty common to have automatic theme based on browser settings

even wikipedia has it now

android api

even docusaurus page https://docusaurus.io/ seems to have it

if possible it will be really good addition for the docs so newcomers don't get flashbanged when opening the site

also when docusaurus page has it I'm guessing it should not be that difficult to implement, but I might be way off