This blew my mind

CSS container queries can use the `ch` unit (character width) inside `calc()` expressions, enabling layouts that are aware of both container size and font size. Unlike media queries where `ch` resolves to a fixed browser default, in container queries `ch` is derived from the container's font size. This means setting a breakpoint like `30ch` per column ensures columns never get too narrow for readable text, and if the font size changes (e.g., via fluid typography with `clamp()`), the layout breakpoints scale proportionally — creating truly font-aware responsive layouts.