<div class="grid-container">
  <div class="grid-item item1">1</div>
  <div class="grid-item item2">span 2</div>
  <div class="grid-item item3">5/8</div>
</div>

.grid-container {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  background-color: #ccc;
}

.grid-item {
  margin: 10px;
  padding: 10px;
  background-color: yellow;
}

.item1 {
  grid-column: 1
}

.item2 {
  grid-column: span 2
}

.item3 {
  grid-column: 5 / 8
}