#btop-but:before {
  position: absolute;
  content: "";
  background: #fff;
  width: 37px;
  height: 38px;
  top: 2px;
  left: 1px;
  border-radius: 4px;
  z-index: -1;
  box-shadow: 0 0 5px 2px #000;
}

#btop-but {
  position: fixed;
  bottom: -4px;
  right: 7px;
  font-size: 40px;
  line-height: 38px;
  height: 54px;
  z-index: 9999;
  transition: all .3s;
  text-shadow: none;
  opacity: .7;
}

@media (hover: hover) and (pointer: fine) {
  #btop-but:hover {
    opacity: 1;
    transition: all .3s;
  }
}

#btop-but a {
  color: #ff0000 !important;
}