online css checker

The tool analyzes CSS code to identify syntax errors, invalid property names and values, and at-rule or selector issues. It also detects duplicate declarations and potential conflicts, while offering basic guidance on compatibility and best practices.

Conceptually, the system parses the stylesheet into an internal structure, validates each rule against a reference of supported properties, values, and at-rules, and aggregates findings by severity. It estimates selector specificity and highlights opportunities to simplify or refactor rules for maintainability.

Who benefits: front-end developers seeking quick feedback during coding, QA engineers validating style sheets before merges, and code reviewers enforcing consistency with coding standards. Unique value lies in structured reports that combine precise location data with concrete fix suggestions, enabling faster iteration and CI integration. Core features include syntax checks, property/value validation, duplicate detection, specificity estimation, and optional lint-style guidance. Typical use cases include validating new components, auditing style sheets for regressions, and preparing CSS for production with quality gates.

The tool emphasizes automation and reproducibility, producing machine-usable outputs for pipelines and human-readable summaries for team reviews. It integrates with existing CSS standards and can be extended with custom rule sets to match project conventions.