Check CSS declaration values against CSSTree property grammars.
Your input
Outputs are cleared when the input changes.
Result
Enter your data or use the example, then run the tool.
Worked example
The sample distinguishes an invalid color, an unchecked custom property and an unknown property.
Method
CSSTree parses the stylesheet and lexer.matchProperty checks each known property value using bundled MDN data. Location columns start at one. CSS is never inserted into the page.
Limits
CSS ≤100,000 characters / 20,000 AST nodes. Custom and unknown properties are explicitly unchecked, not invalid by default. Parser recovery is reported separately. New syntax may exceed the pinned grammar; this is not a browser compatibility guarantee or complete stylesheet conformance check.
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