div.circle-wrap
  - for (var x =1; x <= 12; x++)
    div.row
      - for (var y = 1; y <= 12; y++)
        div.circle

@mixin center {
    display: flex;
    align-items: center;
    justify-content: center;
  }
  
  body {
    @include center;
    height: 100vh;
    background-image: linear-gradient(45deg, #00dbde 0%, #fc00ff 100%)
  }
  
  .row {
    display: flex;
  }
  
  .circle {
    width: 10px;
    height: 10px;
    background: #fff;
    margin: 5px 10px;
    border-radius: 50%;
    transform-origin: top center;
    animation: spin 1s linear infinite;
  }
    
  @keyframes spin {
    0%{transform: scale(1.1) rotate(0deg)}
    50%{transform: scale(0.2) rotate(180deg)}
    100%{transform: scale(1.1) rotate(360deg)}
  }
  /*   .row:nth-child(1) .circle {animation-delay: 100ms}
  .row:nth-child(2) .circle {animation-delay: 200ms}
  .row:nth-child(3) .circle {animation-delay: 300ms}
  .row:nth-child(4) .circle {animation-delay: 400ms} */
  @for $i from 1 through 12 {
    .row:nth-child(#{$i}) .circle {animation-delay: 100ms * $i}
    }