// Why does a closed panel still react?
// Teaching excerpts; see the explanation and boundaries on the episode page.

// One signal. One cleanup.
const c = new AbortController();
window.addEventListener(
  "resize", () => layout(panel),
  { signal: c.signal }
);
return () => {
  c.abort();
  panel.remove();
};

// Or keep the same function.
const onResize = () => layout(panel);
window.addEventListener(
  "resize", onResize
);
// On close:
window.removeEventListener(
  "resize", onResize
);