How I Built a Tiny Tool That Makes Responsive Design Feel Effortless

A frontend developer shares the journey of building Breakpoint Overlay, an open-source widget that displays active CSS breakpoints in real-time during development. The tool addresses the inefficiency of manually checking viewport widths during responsive design implementation by showing breakpoint information as an unobtrusive badge overlay. Built with zero dependencies using Shadow DOM for encapsulation and requestAnimationFrame for performance, it features keyboard shortcuts and viewport metrics. The author discusses technical decisions like choosing resize events over ResizeObserver, managing scope creep during MVP development, and learning monorepo architecture. The tool is available on GitHub and npm.