Allow to switch to Tailwind CSS default Dark mode strategy

[forty]

Hello,

I noticed that congo uses the "class" darkmode strategy https://github.com/jpanther/congo/blob/dev/tailwind.config.js#L8 which apparently is the ancestor of the "selector" strategy https://tailwindcss.com/docs/dark-mode#toggling-dark-mode-manually

However I don't like relying on JS for things that don't require it and here it also causes flashes of unstyled content (my understanding is that the JS messing with the DOM early on load causes this?). Do you think it would be possible to have the option to switch to Tailwind's default dark mode strategy simply using the prefers-color-scheme CSS media feature? (I don't know how that would work, I guess the CSS would be compiled for both approaches and then some options to switch to one or the other?)

Thanks!

Some similar comment in the past: #102 (comment)