First of all, thank you for this very handy ppx 😄

While trying it on our project, we faced a parse error issue Utils.ParseError("Your Tailwind CSS file could not be parsed. Please double-check to make sure it's valid CSS.") that seems to be caused by the @-webkit-keyframes rule (and could be probably be triggered by other rules vendor prefixed).

Since the rules are hardcoded (and validated) here: https://github.com/dylanirlbeck/tailwind-ppx/blob/master/src/ppx/css_parser/css_lexer.ml#L153 it might out of the scope to support prefixed rules though 😕