.back-to-top {
  position: fixed;
  width: 3rem;
  height: 3rem;
  right: 5.2rem;
  bottom: 1.875rem;
  z-index: 9999;
}
.back-to-top i {
  color: #fff;
  font-size: 1rem;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.back-to-bottom {
  position: fixed;
  width: 3rem;
  height: 3rem;
  right: 1.875rem;
  bottom: 1.875rem;
  z-index: 9999;
}
.back-to-bottom i {
  color: #fff;
  font-size: 1rem;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}