.back-to-top {
  position: fixed;
  left: 18px;
  bottom: 20px;
  width: 44px;
  height: 44px;
  border: 1px solid rgba(119, 119, 119, 0.38);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.16);
  backdrop-filter: blur(2px);
  cursor: pointer;
  z-index: 80;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition:
    opacity 0.25s ease,
    transform 0.25s ease,
    border-color 0.25s ease,
    background-color 0.25s ease;
}

.back-to-top::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 56%;
  width: 12px;
  height: 12px;
  border-left: 2px solid rgba(140, 140, 140, 0.85);
  border-top: 2px solid rgba(140, 140, 140, 0.85);
  transform: translate(-50%, -50%) rotate(45deg);
  transition: border-color 0.25s ease;
}

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

.back-to-top:hover,
.back-to-top:focus-visible {
  border-color: rgba(231, 119, 47, 0.55);
  background: rgba(60, 24, 74, 0.2);
}

.back-to-top:hover::before,
.back-to-top:focus-visible::before {
  border-left-color: #e7772f;
  border-top-color: #e7772f;
}