a.fr-scroll-to-top {
  position: fixed;
  bottom: 40px;
  right: 60px;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s, visibility 0.3s;
}

a.fr-scroll-to-top.show {
  opacity: 1;
  visibility: visible;
}