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html, body {
  padding: 0;
  margin: 0;
  width: 100vw;
  height: 100vh;
  position: relative;
  overflow: hidden;
  background: linear-gradient(#123, #111);
}
.kartanesi {
  --size: 1vw;
  width: var(--size);
  height: var(--size);
  background: white;
  border-radius: 50%;
  position: absolute;
  top: -5vh;
}

@keyframes karyagisi {
  0% {
    transform: translate3d(0, 0, 0);
  }
  100% {
    transform: translate3d(0, 110vh, 0);
  }
}

@for $i from 1 through 50 {
  .kartanesi:nth-child(#{$i}) {
    --size: #{random(5) * 0.2}vw;
    --left-ini: #{random(20) - 10}vw;
    --left-end: #{random(20) - 10}vw;
    left: #{random(100)}vw;
    animation: karyagisi #{5 + random(10)}s linear infinite;
    animation-delay: -#{random(10)}s;
  }
}

.kartanesi:nth-child(6n) {
  filter: blur(1px);
}
View Compiled

External CSS

  1. https://codepen.io/wolkanca/pen/wvgOPWb

External JavaScript

  1. https://codepen.io/wolkanca/pen/wvgOPWb