/* Full‑screen overlay */
#intro-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: black;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  opacity: 1.8;
  transition: opacity .7s ease;
}

/* Hidden state */
#intro-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}