CSS Grid Generator Online | Visual Grid Layout Tool

.grid-container {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 1fr 1fr 1fr;
  column-gap: 10px;
  row-gap: 10px;
  justify-items: stretch;
  align-items: stretch;
}

<div class="grid-container">
  <div class="grid-item grid-item-1">1</div>
  <div class="grid-item grid-item-2">2</div>
  <div class="grid-item grid-item-3">3</div>
  <div class="grid-item grid-item-4">4</div>
  <div class="grid-item grid-item-5">5</div>
  <div class="grid-item grid-item-6">6</div>
  <div class="grid-item grid-item-7">7</div>
  <div class="grid-item grid-item-8">8</div>
  <div class="grid-item grid-item-9">9</div>
</div>