What do you think tailwind is?

It's a utility to generate deduped/treeshacken css classes - according to a config file the parent mentioned

It's not some grand framework or something.

It's literally doing exactly what the grand parent said. Define root css variables, and generate the applicable/used css classes that were used in the code

The poster I responded to, specifically asked for how to implement this in tailwind, with a worry about "do you really style each component separately for dark mode? Repeating the same modifiers over and over?"

I simply answered his question - tailwind is indeed just plain old CSS with a more ergonomic DX.