body {
  min-height: 300px;
  margin: 0;
  background: #e0f7fa;
}

.trail {
  position: absolute;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  pointer-events: none;
  z-index: 9999;
  transition: background 0.2s, opacity 0.2s;
  will-change: left, top, width, height, background, opacity;
}