Following up on this:
I have managed to get tailwindcss working following the meteor/examples github here
the new JIT engine is working perfect when meteor does the initial build.
The normal filesize is reduced from 335kb to about 4kb as expected.
The problem arises when changes are made during dev, the JIT engine fails to react to the file change and regenerate the .css file.
I don’t know enough about controlling the postcss build process to suggest a fix.
Perhaps this is also due to some file caching?
Anyone more knowledgeable have any ideas?