I think it's explained here: https://nextjs.org/docs/basic-features/built-in-css-support https://nextjs.org/docs/basic-features/built-in-css-support Basically

I think it's explained here: https://nextjs.org/docs/basic-features/built-in-css-support https://nextjs.org/docs/basic-features/built-in-css-support Basically strong encouragement and support for CSS modules, but some other escape hatches and approaches are supported.