CodePen Embed - CSS 'gap' property.

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

.container {
  display: grid;
  grid: '. . .';
  gap: 16px; /* ⬅️ */
  /* row-gap: 16px; */
  /* column-gap: 16px; */
  border: 16px solid silver;
  background: royalblue;
}
.item { 
  padding: 12px;
  background: white; 
}

This Pen is owned by Jeong, ChanMyeong on CodePen.

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