商品一覧（4列グリッド）のCSS実装

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

.grid-container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 16px;
  width: 100%;
  height: 500px;
}

.item-1 { grid-area: 1 / 1 / 2 / 2; }
.item-2 { grid-area: 1 / 2 / 2 / 3; }
.item-3 { grid-area: 1 / 3 / 2 / 4; }
.item-4 { grid-area: 1 / 4 / 2 / 5; }
.item-5 { grid-area: 2 / 1 / 3 / 2; }
.item-6 { grid-area: 2 / 2 / 3 / 3; }
.item-7 { grid-area: 2 / 3 / 3 / 4; }
.item-8 { grid-area: 2 / 4 / 3 / 5; }

@media (max-width: 768px) {
  .grid-container {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
    height: auto;
  }
  .grid-container > * {
    grid-area: auto;
  }
}