<div class="checkerboard">
  <div class="checkerboard_container">
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
  </div>
</div>
body {
  margin: 0;
}

.checkerboard {
  width: 100%;
  height: 100vh;
  background: url("https://evers-dev2.co.uk/images/ashley-evers-swindell-canada-2018.jpg")
    center center no-repeat;
  background-size: cover;
}

.checkerboard_container {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
}

.square {
  width: calc(100% / 7);
  height: 25%;

  animation-name: fadeOut;
  animation-duration: 0.25s;
  animation-fill-mode: forwards;

  &:nth-child(odd) {
    // background: #598E94;
    background: rgba(89,142,148,0.95);
  }

  &:nth-child(even) {
    // background: #ffffff;
    background: rgba(255,255,255,0.95);
  }
}

@keyframes fadeOut {
  to {
    opacity: 0;
  }
}

$columns: 7;
$rows: 4;
$cells: $columns * $rows;

@for $i from 1 through $cells {
  .checkerboard_container .square:nth-child(#{$i}) {
    animation-delay: (random($cells) / $columns) + s;
  }
}
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