#scrollvalue {
  z-index: 5;
  position: fixed;
  right: 0;
  top: 0;
  width: 8px;
  height: 0px;
  background-color: var(--purple);
  animation: changeValue ease-out;
  animation-timeline: scroll();
}

/* keyframes */
@keyframes changeValue {
  to { height: 100%; }
}