html,
body {
  width: 100%;
  min-height: 100%;
}

body {
  background: #fff;
}

.background-container {
  width: 100%;
  height: 100%;
  background: #fff;
}

.circle-container {
  position: absolute;
  top: 0;
  left: 0;
  width: var(--particle-size);
  height: var(--particle-size);
  transform: translateY(-10vh);
  animation: move-particle var(--move-duration) linear var(--move-delay) infinite;
}

.circle-container .circle {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  mix-blend-mode: normal;
  background: hsl(0, 0%, 68%);
  opacity: var(--particle-opacity, .35);
  box-shadow: 0 0 3px hsla(0, 0%, 60%, .25);
}

@keyframes move-particle {
  from { transform: translate3d(var(--start-x), var(--start-y), 0); }
  to { transform: translate3d(var(--end-x), var(--end-y), 0); }
}

@media (prefers-reduced-motion: reduce) {
  .circle-container,
  .circle-container .circle {
    animation: none;
  }
}