/* BACK TO TOP button */
.back-to-top {
  position: fixed;
  right: var(--s-6);
  bottom: var(--s-6);
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255, 255, 255, 0.2);
  background: rgba(26, 26, 26, 0.2);
  z-index: 1001;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: background var(--ease), border-color var(--ease),
              opacity var(--ease), visibility var(--ease), transform var(--ease);
}

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

.back-to-top:hover {
  background: rgba(26, 26, 26, 0.9);
  border-color: rgba(255, 255, 255, 0.9);
}

.back-to-top__icon {
  display: inline-block;
  width: 18px;
  height: 18px;
  background-color: var(--c-white);
  -webkit-mask: url('../img/icon-arrow-up.svg') no-repeat center / contain;
  mask: url('../img/icon-arrow-up.svg') no-repeat center / contain;
  transition: background-color var(--ease);
}

.back-to-top:hover .back-to-top__icon {
  background-color: var(--c-white);
}