.back-to-top{
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(255, 255, 255, 0.9);
  width: 3.2rem;
  height: 3.2rem;
  opacity: 0.8;
  transition: 0.2s ease-out;
}

.back-to-top span {
  color:gray;
}

.back-to-top:hover {
  opacity: 70%;
  cursor: pointer;
}

.back-to-top:hover span{
  transform: translateY(-3px);
}

.back-to-top:active {
  opacity: 30%;
  cursor: pointer;
}

@media(max-height : 600px){

  .back-to-top {
    background-color: transparent;
  }
  .back-to-top img{
    opacity: 0.2;
  }
}