HTML provides the structure of a webpage, defining elements like headings, paragraphs, and images. CSS is used for styling, controlling layout, colors, fonts, and responsiveness. JavaScript adds interactivity, enabling dynamic content updates, animations, and user interactions. Together, they form the foundation of front-end development, with HTML as the skeleton, CSS as the skin, and JavaScript as the muscles that bring the page to life.

I ensure cross-browser compatibility by using feature detection libraries like Modernizr, writing clean and standardized code, and testing on multiple browsers and devices. I also leverage tools like BrowserStack for automated testing and follow best practices such as using CSS resets and vendor prefixes. Regularly checking compatibility tables like MDN or Can I Use helps me stay updated on browser-specific quirks and supported features.

Responsive design ensures a website adapts to different screen sizes and devices. I implement it using CSS media queries to adjust layouts, flexible grid systems, and scalable images. Frameworks like Bootstrap or Tailwind CSS can streamline this process. I also prioritize mobile-first design, ensuring the site is optimized for smaller screens and progressively enhanced for larger ones. Testing on real devices and using browser developer tools helps refine the responsiveness.

I optimize performance by minimizing HTTP requests, compressing images, and using lazy loading. I also leverage browser caching, minify CSS and JavaScript files, and use Content Delivery Networks (CDNs) for faster asset delivery. Tools like Lighthouse or WebPageTest help identify bottlenecks. Additionally, I prioritize critical rendering paths and defer non-essential scripts to ensure faster page load times and a smoother user experience.

I use browser developer tools to inspect elements, monitor network activity, and debug JavaScript. Console logging helps trace errors, and breakpoints allow step-by-step code execution analysis. For CSS issues, I validate styles using the browser’s computed styles panel. I also rely on version control systems like Git to track changes and isolate issues. Collaboration with team members and referencing documentation are key to resolving complex problems efficiently.