How to fix the `unable to resolve dependency tree` PostCSS and Tailwind issue in Next.js

While setting up a new Next.js project with Tailwind I ran into an issue.

This issue might just be a temporary issue due to configuration problems and libraries versions, but I’m writing this in case someone stumbles on it.

I ran:

npm install tailwindcss postcss-preset-env postcss-flexbugs-fixes

In other words, PostCSS 8.1.13 was required but Next installed 8.1.7.

So I ran

npm install tailwindcss@latest postcss@latest
postcss-preset-env postcss-flexbugs-fixes

and it worked!