Subscribe to a CSS media query (e.g. dark mode, viewport size) from React. Re-renders when the match changes. SSR-safe — returns `false` on the server.
Let the browser pick the right image for the viewport. `srcset` lists candidates by intrinsic width; `sizes` tells the browser how big the image will render. Cuts mobile data dramatically.
Wrap any wide table in a horizontally-scrolling container. The table itself stays semantic (no display:block hacks that break screen readers); only the wrapper scrolls.