/* Shared UI controls */
.back-to-top {
  position: fixed;
  right: 16px;
  bottom: 16px;
  width: 40px;
  height: 40px;
  border: 1px solid rgba(0, 0, 0, 0.18);
  border-radius: 999px;
  background: rgba(34, 34, 34, 0.72);
  color: #fff;
  font-size: 20px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(6px);
  transition: opacity .16s ease, transform .16s ease, visibility .16s ease, background .16s ease;
  z-index: 25;
}
.back-to-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top:hover {
  background: rgba(34, 34, 34, 0.88);
}