সিএসএস grid-auto-columns

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.container {
  display: grid;
  grid-template-rows: repeat(3, 70px);
  grid-auto-columns: 60px;
  gap: 5px;
}

.container > div {
  background-color: lightgray;
}
</style>
</head>
<body>

<div class="container">
  <div></div>
  <div></div>
  <div></div>
</div>

</body>
</html>