/* "How did you hear about us?": the "something else" box only once that is
   picked. A selector, not a script; a phone too old for :has() draws the box
   all the time, with its "only if you picked" hint. */
@supports selector(:has(*)) {
  [data-heard-about]:not(:has(option[value="other"]:checked)) [data-heard-other] { display: none; }
  [data-heard-about]:has(option[value="other"]:checked) [data-heard-other] p { display: none; }
}