body {
  /*background: #6699cc;   add a blue background color */
  overflow: hidden;
}

.snow {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0.8vw;  /* make the snowflakes larger */
  height: 0.8vw;
  border-radius: 50%;
  background: white;
  box-shadow: 0 0 5px white;  /* add a shadow to the snowflakes */
  animation: snow 50s linear infinite;
  animation-delay: 0s;
}

@keyframes snow {
  0% {
    top: -100%;
    visibility: visible;
  }
  /* and so on */
  100% {
    top: 100%;
  }
}