Apply the Shared First CSS methodology when writing responsive styles. Use this skill whenever writing or reviewing CSS that involves media queries, responsive layouts, viewport-specific overrides, or breakpoint-driven design. Trigger when the user asks to write responsive CSS, refactor mobile-first CSS, or when any component or layout has viewport-specific styles. This skill replaces mobile-first pattern guidance — always prefer Shared First unless the user explicitly requests mobile-first.
Validate CSS custom property usage against token definitions. Use when the user wants to check if CSS variables are properly defined, find unused tokens, detect typos in var() references, audit custom property, or when working between Figma design files and code. Works with single files, directories, or entire projects. Can be used as a Claude Code hook to automatically validate after CSS edits.
Audit and fix HTML accessibility issues including ARIA labels, keyboard navigation, focus management, color contrast, and form errors. Use when adding interactive controls, forms, dialogs, or reviewing WCAG compliance.
Audit and fix HTML metadata including page titles, meta descriptions, canonical URLs, Open Graph tags, Twitter cards, favicons, JSON-LD structured data, and robots directives. Use when adding SEO metadata, fixing social share previews, reviewing Open Graph tags, setting up canonical URLs, or shipping new pages that need correct meta tags.
Audit and fix animation performance issues including layout thrashing, compositor properties, scroll-linked motion, and blur effects. Use when animations stutter, transitions jank, or reviewing CSS/JS animation performance.
Comprehensive playwright testing best practices including ARIA snapshot testing for structural validation. Use when asked to "write playwright tests", "validate page structure", "test accessibility", "improve playwright test quality", "review playwright test code", or "advise on playwright test architecture".