Cross-Browser & Testing
Master cross-browser CSS — feature detection, progressive enhancement, vendor prefixes, and visual regression testing.
50 min•By Priygop Team•Last updated: Feb 2026
Cross-Browser Strategies
- Feature Detection: @supports (display: grid) { ... } — use modern features with fallbacks. Progressive enhancement over graceful degradation
- Autoprefixer: PostCSS plugin that adds vendor prefixes automatically — write standard CSS, build process adds -webkit-, -moz- as needed based on browserslist
- Reset vs Normalize: CSS Reset (Eric Meyer's) removes ALL defaults. Normalize.css preserves useful defaults and fixes browser inconsistencies. Modern: use both strategically
- Browserslist: Define target browsers in package.json — '> 1%, last 2 versions, not dead'. Autoprefixer and Babel use this to determine required polyfills
- Can I Use: Check feature support before using — caniuse.com shows browser support percentages. Critical for deciding whether to use a feature or need a fallback
- Testing Matrix: Chrome, Firefox, Safari, Edge (desktop). Chrome Mobile, Safari iOS (mobile). Test on real devices, not just browser DevTools emulation
Visual Regression Testing
- Screenshot Comparison: Capture screenshots after each change, compare with baseline — detect unintended visual changes. Backstop.js, Percy, Chromatic
- Component Testing: Storybook + Chromatic — test components in isolation, catch visual regressions per component rather than full pages
- Responsive Testing: Test at key breakpoints — 320px (mobile), 768px (tablet), 1024px (laptop), 1440px (desktop). Verify layouts at each breakpoint
- Browser DevTools: Chrome DevTools → CSS Overview — find unused CSS, color contrast issues, font usage. Performance panel for rendering bottlenecks
- Linting: Stylelint catches CSS errors and enforces conventions — property order, naming conventions, no duplicate properties, no unknown values