Web frontend development: HTML5, CSS3, SCSS, Tailwind, accessibility, and performance. Use when working on full web frontend projects, choosing between CSS approaches, or auditing accessibility/performance.
Instalación
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Web frontend development: HTML5, CSS3, SCSS, Tailwind, accessibility, and performance. Use when working on full web frontend projects, choosing between CSS approaches, or auditing accessibility/performance.
Web Frontend
HTML5
Use semantic elements: <header>, <nav>, <main>, <section>, <article>, <footer>
Every page must have <meta name="viewport" content="width=device-width, initial-scale=1.0">
Include <meta charset="UTF-8"> and descriptive <title>
Images must have alt attributes. Decorative images use alt="".
Form inputs must have associated <label> elements
Use loading="lazy" on below-fold images
ARIA landmarks where appropriate: role="banner", role="navigation", role="main"
CSS3
Mobile-first responsive design with @media breakpoints at 480px, 768px, 1024px
Use CSS custom properties (--var) for theme colors, spacing, and typography
Prefer rem/em over px for typography and spacing
Use display: grid for layouts, flexbox for components
Avoid !important. Use specificity instead.
Dark theme: use prefers-color-scheme: dark media query + CSS variables
SCSS
Nest selectors max 3 levels deep
Use $variables for colors, spacing, breakpoints
Use @mixin for repeated patterns (e.g., media queries, button styles)
Compile to compressed CSS for production
Tailwind CSS
Use utility classes over custom CSS where possible
Responsive prefixes: sm:, md:, lg:, xl:
Dark mode: dark: prefix with class strategy
Custom theme in tailwind.config.js under extend
Use @apply in component classes sparingly - prefer composition
Accessibility
Color contrast ratio: minimum 4.5:1 for normal text, 3:1 for large text
All interactive elements must be keyboard-navigable (Tab, Enter, Escape)
Focus indicators must be visible (never outline: none without replacement)
Screen reader text: .sr-only class for visually hidden labels
aria-label on icon-only buttons and links
aria-expanded on toggle elements
role="status" or aria-live for dynamic content updates
Performance
Minify HTML, CSS, JS for production
Use rel="preload" for critical fonts and above-fold images
Defer non-critical JS with defer or async
Image formats: WebP with JPEG/PNG fallback
CSS containment: contain: layout style paint for off-screen content
