<section class="grid">
  <div class="item">item1</div>
  <div class="item">item2</div>
</section>

.grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: 100px 100px;
  grid-gap: 20px;

  grid-auto-columns: 200px;
  grid-auto-rows: 60px;
  max-width: 800px;
  
  /* Or use minmax for more flexibility:
  
    grid-auto-columns: minmax(200px, auto);
    grid-auto-rows: minmax(60px, auto);
  
  */
  
}

.item:first-child {
  grid-column-start: -1;
}

.item:nth-child(2) {
  grid-row-start: 4;
}