<section class="grid grid1">
  <div class="item">item1</div>
  <div class="item">item2</div>  
  <div class="item">item3</div>
  <div class="item">item4</div>
</section>

<section class="grid grid2">
  <div class="item">item1</div>
  <div class="item">item2</div>  
  <div class="item">item3</div>
  <div class="item">item4</div>
</section>

.grid {
  display: grid;
  grid-gap: 20px;
}

.grid1 {
  grid-template-columns: repeat(4, 100px);
}

.grid2 {
  display: none;
}

/*
.grid2 {
  grid-template-columns: repeat(auto-fit, 100px);
}
*/