Activate this skill when working on: - Building or modifying React/Vue/Next.js applications - Setting up modern JavaScript/TypeScript build tooling - Implementing responsive UI components - Working with CSS frameworks (Tailwind, Bootstrap, custom) - Configuring Webpack, Vite, or other bundlers - Optimizing frontend build processes - Debugging frontend compilation or runtime issues - Implementing state management (Redux, Zustand, Context API) - Working with modern ES6+ JavaScript features