$colors:
  #2196F3,
  #03A9F4,
  #00BCD4,
  #009688,
  #4CAF50,
  #8BC34A,
  #CDDC39,
  #FFEB3B;

body {
  background-color: #3F51B5;
}

.spinner {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 1;
  height: 40px;
  width: 40px;
  transform: translate(-50%, -50%);
}

[class^="ball-"] {
    position: absolute;
    display: block;
    left: 30px;
    width: 12px;
    height: 12px;
    border-radius: 6px;
    transition: all 0.5s;
    animation: circleRotate 4s both infinite;
    transform-origin: 0 250% 0;
}

@keyframes circleRotate {
  0% {
    transform: rotate(0deg);
  }
  100% { 
    transform: rotate(1440deg); 
  }
}

@for $i from 1 through 8 {
  .ball-#{$i} {
    z-index: -#{$i};
    background-color: nth($colors, $i);
    animation-timing-function: cubic-bezier(0.5, 0.3 * $i, 0.9, 0.9);
  }
}