bubles {
  border-radius:100%;
  position: absolute;
  pointer-events: none;
  background: #20e3a2;
  box-shadow:  10px 10px 30px #31c8a2, 
             -10px -10px 30px #31c8a2;
  transform: translate(-50%, -50%);
  animation: colorgen 1s infinite;
  z-index: 10000;
}

@keyframes colorgen {
  0% {
    opacity: 1;
    filter: hue-rotate(0deg);
  }
  100% {
    opacity: 0;
    filter: hue-rotate(270deg);
  }
}