#registerButtonIndex {
  position: relative;
  overflow: hidden;
  background: #0f1117;
  color: #fff;
}

#registerButtonIndex::before {
  content: "";
  position: absolute;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(0, 122, 196, 0.8) 20%, transparent 60%);
  top: var(--y);
  left: var(--x);
  transform: translate(-50%, -50%) scale(0);
  transition: transform 0.4s ease;
  z-index: 0;
}

#registerButtonIndex * {
  position: relative;
  z-index: 1;
}

#registerButtonIndex:hover::before {
  transform: translate(-50%, -50%) scale(1);
}