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| Concern | What to inspect | Typical failure |
|---|---|---|
| Core behavior | Container Queries | Container queries are powerful because the same component can live in a narrow sidebar and a wide main column without relying on global viewport breakpoints. |
| Production test | Real content and constraints | The rule works only for the demo values |
| Maintenance | Scope and override path | A later fix creates another exception |
In production, Container queries are powerful because the same component can live in a narrow sidebar and a wide main column without relying on global viewport breakpoints. That is the kind of bug that survives visual spot checks because the stylesheet is syntactically valid while the layout contract is wrong.
<style>.card-shell { container-type:inline-size; }</style><main class="card-shell">Example content</main>
Engineering judgment: The query sees the relevant container, not the entire page. Establishing the correct container boundary is part of the component architecture.
A good CSS change narrows the problem. The query sees the relevant container, not the entire page. Establishing the correct container boundary is part of the component architecture. This keeps the rule understandable when content, theme, or viewport conditions change later.
<style>@container (min-width: 36rem) { .card { grid-template-columns: 8rem 1fr; } }</style><main class="card">Example content</main>
In production, Container queries are powerful because the same component can live in a narrow sidebar and a wide main column without relying on global viewport breakpoints. That is the kind of bug that survives visual spot checks because the stylesheet is syntactically valid while the layout contract is wrong.
<style>.layout { container:card / inline-size; }</style><main class="layout">Example content</main>
Named container is useful here because it demonstrates container queries under a concrete input rather than as an abstract property list.
<style>@container card (min-width: 40rem) { .card__actions { display:flex; } }</style><main class="card__actions">Example content</main>
Named query is useful here because it demonstrates container queries under a concrete input rather than as an abstract property list.
Finish the lesson once you have worked through the material. This awards ★ 30 XP.