SOURCE

    <div class="grid-container">
        <div class="item1">1</div>
        <div class="item2">2</div>
        <div class="item3">3</div>
        <div class="item4">4</div>
       
    </div>

.grid-container{
  display: grid;
  grid-template-columns: 50px 50px 50px;
  grid-template-rows: 50px 50px 50px;
  height: 100%;
  background: #d4d4d4;
  grid-gap: 10px;
  grid-template-areas: 
    'a  a  b '
    'd  .  b '
    'd  c  c '
}
.grid-container > div {
  border: 1px grey solid;
}
.item1{
  grid-area: a;
}
.item2{
  grid-area: b;
}
.item3{
  grid-area: c;
}
.item4{
  grid-area: d;
}

html,body{
  height: 100%;
  width: 100%;
}