#scroll-progress{
  display: none;
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--zone-1, #7a5fa9), var(--zone-2, #5255a5));
  z-index: 10000;
  transition: width 0.1s linear, background 0.4s ease;
}
@media (prefers-reduced-motion: reduce){
  #scroll-progress{ transition: none; }
}