.explosion {
  position: absolute;
  width: 600px;
  height: 600px;
  pointer-events: none;
}
.explosion .particle {
  position: absolute;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  animation: pop 1s reverse forwards;
}

@keyframes pop {
  from {
    opacity: 0;
  }
  to {
    top: 50%;
    left: 50%;
    opacity: 1;
  }
}