DropCSS

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; for these infrequent cases, please start a discussion. While the HTML spec allows html, head, body and tbody to be implied/omitted, DropCSS makes no such assumptions; selectors will only be retained for tags that can be parsed from provided markup. It's also a good idea to run your CSS through a structural optimizer like clean-CSS, csso, cssnano or crass to re-group selectors, merge redundant rules, etc. It probably makes sense to do this after DropCSS, which can leave redundant blocks.