CSS Validator (Syntax Checker)

A stray brace or a missing semicolon can silently switch off half a stylesheet, because browsers skip what they cannot parse instead of reporting it. This checker reads your CSS the way a browser tokenizes it and lists every problem with its line and column: unclosed braces, strings and comments, missing semicolons, unknown properties (with "did you mean" suggestions), invalid units and hex colours, unitless lengths, empty rules, duplicate properties and misplaced @import or @charset. Modern CSS — nesting, @layer, @container, :has() — is understood.

How to use this tool

1. Paste your stylesheet (or a part of it).
2. Read the verdict and the table of messages, sorted by line.
3. Go to each line and column; errors break parsing, warnings are likely mistakes, notes are tips.
4. Choose "Errors only" to focus on what breaks the stylesheet.

Formula

stylesheet → rules → selector { property: value; … }

Severity: an error means browsers drop that declaration or rule (or everything up to the next closing brace); a warning means the CSS parses but is probably not what you meant, such as an unknown property or a duplicate; a note is information only. Vendor-prefixed properties (-webkit-…) and custom properties (--name) are accepted as written.

Example

The sample has 3 errors and 2 warnings: colr on line 4 is an unknown property ("did you mean color?"); margin: 0 on line 5 has no semicolon, so it swallows padding on line 6; 8pz on line 10 has an unknown unit; #fffff on line 11 has five hex digits; and :hovr on line 13 is an unknown pseudo-class. It has 4 style rules, 8 declarations (margin and padding count as one, because they ran together) and one !important.