* use `~/.cache/tailwindcss` as default touch dir
When more tools catch up with the latest postcss dependency tracking,
then we probably don't even need this anymore. However, it is a good
practice to put (global) caches in ~/.cache and (global) configs in
~/.config
Fixes: #4569
* change test to verify @tailwind base slightly
Because of some changes in tailwind itself, the base selector contains a
ton of new --tw-* custom properties. Keeping this up to date might be a
bit of an annoying challenge. So instead we now check for the selector
to be present.
* add `tmp` package
* use a (simple) temporary file, instead of a full cache dir
38a71d8d60