.liboit-back-to-top {
  position: fixed;
  right: max(22px, env(safe-area-inset-right));
  bottom: calc(22px + env(safe-area-inset-bottom));
  z-index: 15;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  width: 58px;
  height: 62px;
  padding: 6px;
  border: 1px solid #ffffff70;
  border-radius: 16px;
  background: #17382f;
  color: #fff;
  box-shadow: 0 4px 18px #17382f26;
  font: 600 11px/1.4 BookSans, 'Malgun Gothic', sans-serif;
  cursor: pointer;
  touch-action: manipulation;
}
.liboit-back-to-top[hidden] { display: none; }
.liboit-back-to-top:hover { background: #28634e; }
.liboit-back-to-top:active { transform: translateY(1px); }
.liboit-back-to-top:focus-visible { outline: 3px solid #c15a23; outline-offset: 4px; }
@media (max-width: 600px) {
  .liboit-back-to-top { right: max(14px, env(safe-area-inset-right)); bottom: calc(16px + env(safe-area-inset-bottom)); width: 52px; height: 56px; border-radius: 14px; }
}