CSS Container Queries インタラクティブプレイグラウンド

Create an interactive playground to explore CSS Container Queries (size queries only). Include a resizable parent container with three child cards. The children should have styles that change based on the parent's width: narrow, medium, and wide breakpoints (e.g., <300px, 300-500px, >500px). Show the current container width and breakpoint label. Use only container query syntax (no media queries). Keep the code self-contained and visually clean.