css grid. Расположение внутри контейнера

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

.grid {
  display: grid;
  height: 100vh;
}

.grid__item {
  border: 1px solid #00f;
  padding: 1rem;
}

.grid__item:nth-child(1) {
  grid-column: 1 / 4;
  grid-row: 1 / 3;
}

.grid__item:nth-child(2) {
  grid-column: 4 / 6;
  grid-row: 1 / 2;
}

.grid__item:nth-child(3) {
  grid-column: 4 / 6;
  grid-row: 2 / 3;
}

<div class="grid">
  <div class="grid__item">1</div>
  <div class="grid__item">2</div>
  <div class="grid__item">3</div>
</div>