#マウスストーカー {
  pointer-events: none;
  position: fixed;
  top: -10px;
  left: -10px;
  width: 20px;
  height: 20px;
  background: darkgreen;
  border-radius: 50%;
  transform: translate(0, 0);
  transition: transform 0.2s;
  transition-timing-function: ease-out;
  z-index: 999;
}