html.drop-on body::after {
  content: "放開就加入書庫";
  position: fixed; inset: 16px; z-index: 100;
  display: flex; align-items: center; justify-content: center;
  border: 2px dashed var(--acc); background: rgba(18, 19, 20, .82);
  color: var(--ink); font-size: 22px; font-weight: 900;
  pointer-events: none;
}