Container queries are perhaps the most significant addition to CSS since Flexbox and Grid. They allow components to respond to the size of their container rather than the viewport, enabling truly modular responsive design.

With the @container rule and the container-type property, you can create components that adapt their layout based on available space. This is particularly powerful for design systems and component libraries.

Browser support is now universal, and combined with CSS Nesting and the :has() selector, we’re entering a golden age of CSS where many patterns that required JavaScript can now be achieved with pure CSS.