GitHub - leeoniya/dropcss: An exceptionally fast, thorough and tiny unused-CSS cleaner

DropCSS takes your HTML and CSS as input and returns only the used CSS as output. Its custom HTML and CSS parsers are highly optimized for the 99% use case and thus avoid the overhead of handling malformed markup or stylesheets, so well-formed input is required. There is minimal handling for complex escaping rules, so there will always exist cases of valid input that cannot be processed by DropCSS