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CSS Validation Guidelines
Syntax Rules
- Use proper selector syntax
- End property declarations with semicolons
- Match opening and closing braces
- Use valid property names and values
- Properly quote string values
Best Practices
- Use meaningful class and ID names
- Organize CSS logically
- Avoid !important when possible
- Use shorthand properties
- Keep specificity low
Compatibility
- Test across different browsers
- Use vendor prefixes when needed
- Provide fallbacks for new features
- Consider progressive enhancement
- Validate with online tools
CSS Validation Reference
Common Errors
- Missing semicolons after properties
- Unmatched opening/closing braces
- Invalid property or value names
- Incorrect color format syntax
- Missing quotes around string values
Validation Tools
- W3C CSS Validator
- Browser Developer Tools
- CSS Lint tools
- Autoprefixer for vendor prefixes
- CSS minification tools
Optimization Tips
- Combine and minify CSS files
- Remove unused CSS rules
- Use efficient selectors
- Optimize for critical rendering path
- Use CSS preprocessors wisely