FAQ

Does my CSS leave the browser? Formatting and validation run locally. A URL in the input box is the exception: the browser requests that address directly, and the remote host can refuse the request.

Why did a URL fail? Most sites omit the CORS headers a browser page needs. Save the file and drop it in, or paste the stylesheet instead.

What does Fix CSS change? It closes unclosed braces, strings, comments, and functions, drops a stray }, inserts a missing colon or semicolon, quotes a bare url() that contains spaces, and moves @charset to the first line. A declaration sitting outside any rule is wrapped in :root. An invalid color is reported and left in place.

Will it rewrite my values? No. It does not expand shorthands, sort properties, or add vendor prefixes. Whitespace is normalized, property names are lowercased, and a valid hex color is lowercased. Custom property names, strings, and comments stay as written.

Why was a property flagged? Warnings are for names this tool does not recognize, a property repeated in the same rule, an empty rule, and an @import that follows other rules. Switch Validation to Errors Only to hide them. A name starting with -- or - is not treated as unknown.