.top_block {
  position: fixed;
  right: 0.5rem;
  bottom: 4.5rem;
  display: none;
}

.top_block .top_link {
  width: 40px;
  height: 40px;
  line-height: 40px;
  display: block;
}

@media (max-width: 991.98px) {
  .top_block {
    bottom: 0.5rem;
  }
}