#preload {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-flow: wrap nowrap;
  justify-content: center;
  align-items: center;
  padding: 0;
  margin: 0;
  list-style: none;
}

#preload li {
  width: 5px;
  height: 38px;
  padding: 0;
  margin: 0;
  background-color: #4c7cc3;
  transform-origin: center;
  will-change: transform;
}

#preload li:nth-child(1) {
  animation: preloadRect 0.5s ease infinite alternate;
}

#preload li:nth-child(2) {
  margin-left: 8px;
  animation: preloadRect 0.5s 0.2s ease infinite alternate;
}

#preload li:nth-child(3) {
  margin-left: 8px;
  animation: preloadRect 0.5s 0.4s ease infinite alternate;
}

@keyframes preloadRect {
  from {
    transform: scaleY(1);
  }

  to {
    transform: scaleY(0.2);
  }
}