/* ═══════════════════════════════════════════
   BACK TO TOP – trang chủ
═══════════════════════════════════════════ */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 92px;
  width: 46px;
  height: 46px;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: var(--white);
  color: var(--gold);
  cursor: pointer;
  z-index: 2090;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  box-shadow: var(--sh-sm);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition:
    opacity 0.3s var(--ease),
    transform 0.3s var(--ease),
    visibility 0.3s,
    background 0.2s var(--ease),
    border-color 0.2s var(--ease),
    color 0.2s var(--ease);
  pointer-events: none;
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  pointer-events: auto;
}

.back-to-top:hover {
  background: var(--gold-light);
  border-color: var(--gold);
  color: var(--gold-dark);
}

.back-to-top:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 2px;
}

@media (max-width: 575px) {
  .back-to-top {
    right: 16px;
    bottom: 82px;
    width: 42px;
    height: 42px;
    font-size: 0.9rem;
  }
}