#backToTopButton {
  position: fixed;
  bottom: 1rem;
  right: 2.5rem;

  opacity: 0;
  visibility: hidden;

  transform: translateY(100%);
  transition: 200ms;

  z-index: 999;
}

#backToTopButton svg circle {
  filter: brightness(1.1);
}

#backToTopButton.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}