CSS Container Queries

CSS Container Queries — Style elements based on parent container size, not viewport. True component-level responsive design. The guide walks through Container Setup. Define container: `container-type: inline-size` or `container: card / inline-size`. Query: `@container card (min-width: 400px) { ... }`. Container query length units: cqw (1% container width), cqh, cqi, cqb, cqmin, cqmax. Use for: reusable components that adapt to their placement (sidebar vs main content). The guide is organized into 1 sections that build on each other, each pairing a prose explanation with real CSS you can use as-is. Related guides: CSS Introduction, CSS Selectors, CSS Box Model, CSS Flexbox, CSS Grid. This is one of 68 CSS guides on CSS Reference — see the full list on the guides page. Look up any property mentioned in this guide from the search page or the CSS Reference homepage.