Here is an example off the top of my head, while on iphone:

.card { @apply flex flex-row shadow rounded-md p-4; @screen md { @apply flex-col p-6; } yada... yada... }

then in tailwind config, point the purge path to your html file(s) to purge.

End result is css file with no more and no less than what you need, and in the web inspector you see clean HTML markup and clean CSS declarations.

edit: typo