<div class="wrapper">
  <div class="box box-1">1.</div>
  <div class="box box-2">2.</div>
  <div class="box box-3">3.</div>
  <div class="box box-4">4.</div>
  <div class="box box-5">5.</div>
  <div class="box box-6">6.</div>
</div>

.wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 200px 200px;
  grid-gap: 10px;
  max-width: 1000px;
  margin: 50px auto;
}

.box {
  color: white;
  text-align: center;
  font-size: 30px;
  padding: 25px;
}

.box-1 {
  background-color: cornflowerblue;
}

.box-2 {
  background-color: crimson;
}

.box-3 {
  background-color: lightseagreen;
}

.box-4 {
  background-color: darkorange;
}

.box-5 {
  background-color: limegreen;
}

.box-6 {
  background-color: darkorchid;
}