<div class="grid">
  <div class="item">
    <div class="subitem">1</div>
    <div class="subitem">2</div>
    <div class="subitem">3</div>
    <div class="subitem">4</div>
    <div class="subitem">5</div>
    <div class="subitem">6</div>
    <div class="subitem">7</div>
    <div class="subitem">8</div>
    <div class="subitem">9</div>
    <div class="subitem">10</div>
    <div class="subitem">11</div>
    <div class="subitem">12</div>
  </div>
</div>
.grid {
  width:100%;
  background:#dddddd;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(4, minmax(100px, auto));
  grid-column-gap: 10px;
  grid-row-gap: 10px;
}

.item {
  display: grid;
  grid-column: 2 / 7;
  grid-row: 2 / 4;
  grid-template-columns: subgrid;
  grid-auto-rows: minmax(100px, auto);
   grid-column-gap: 10px;
  grid-row-gap: 10px;
}

.subitem{
  w-full;
  background:#aaaaaa;
  padding:1rem;
}

External CSS

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External JavaScript

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