Unminified CSS wastes bandwidth with whitespace, comments, and verbose syntax—minification delivers the same styles in significantly fewer bytes.
Quick Reference
- Enable minification in build tool (Vite, webpack, etc.)
- Use cssnano or lightningcss for PostCSS pipelines
- Typical reduction: 20-40% file size savings
- Combine with Gzip/Brotli for maximum compression
Check
Verify that all CSS files are minified in production to reduce file size, eliminate whitespace, and improve page load performance.
Fix
Set up CSS minification in your build process using tools like cssnano, CleanCSS, or built-in framework minification to compress CSS files.
Explain
Explain how CSS minification improves website performance by reducing file sizes, decreasing bandwidth usage, and speeding up page load times.
Code Review
Review stylesheets, component styles, and responsive states related to Minify all CSS files. Flag exact selectors, declarations, or breakpoints that violate the rule in the rendered UI.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/css/css-minification