What problem does it solve? Building modern web interfaces requires juggling design systems, component architecture, responsive layouts, accessibility compliance, and performance optimization all at once. This Skill provides a structured runbook and reference guides so frontend work follows consistent, high-quality standards instead of ad-hoc decisions. ## Core Features & Use Cases - Six-Phase Development Workflow: Guides implementation from UX analysis through design tokens, component composition, state management, motion polish, and final accessibility/performance audits. - Design System Foundations: Provides typography scales, color palettes, glassmorphism patterns, elevation layers, and 8pt spacing grids for cohesive visual design. - React & TypeScript Patterns: Includes reusable component primitives (Button, Tabs), custom hooks (useDebounce, useMediaQuery), compound component patterns, and class composition with clsx and tailwind-merge. - Performance & Accessibility Auditing: Covers Core Web Vitals targets (LCP, INP, CLS), React memoization strategies, and a WCAG 2.1 AA checklist for contrast, keyboard navigation, and ARIA. - Use Case: When asked to build a dashboard page, the agent follows the workflow to define design tokens, compose typed components, add Framer Motion transitions, and verify keyboard navigation and contrast ratios before finishing. ## Quick Start Build a responsive pricing page with React, Tailwind CSS, and smooth animations following the frontend developer workflow.