.back-to-top {
  width: 34px;
  height: 33px;
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 9999;
  cursor: pointer;
  display: none;
}
.back-to-top img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 1/1;
}
.back-to-top.is-visible {
  display: block;
}