.backtop {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 999;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid rgba(209, 168, 85, 0.6);
  background: rgba(15, 17, 21, 0.85);
  color: #fff;
  font-size: 20px;
  line-height: 44px;
  text-align: center;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.35);
  cursor: pointer;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.25s ease, transform 0.25s ease, background 0.2s ease;
  pointer-events: none;
}

.backtop:hover {
  background: rgba(209, 168, 85, 0.25);
  color: #fff;
}

.backtop.show {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

@media (max-width: 640px) {
  .backtop {
    right: 14px;
    bottom: 14px;
    width: 42px;
    height: 42px;
    line-height: 40px;
  }
}