Frontend
What is Responsive Design?
An approach where layouts adapt fluidly to any screen size using flexible grids, media queries, and scalable images.
Definition
Responsive design builds a single codebase that renders well from a 320px phone to a 4K monitor. Coined by Ethan Marcotte in 2010, it combines fluid grids (percentages, fr units), flexible media (max-width: 100%, srcset), and CSS media queries that adjust layout at breakpoints. Modern CSS pushes further with container queries, clamp() for fluid typography, and intrinsic layouts via Grid and Flexbox. Google's mobile-first indexing made responsiveness an SEO requirement, not just a UX nicety, and frameworks like Tailwind and Bootstrap ship breakpoint systems out of the box.