グリッドレイアウト

display: grid; プロパティを使ってアイテムを複雑に配置します。

デモ

See the Pen layout-5 by logsuke (@design-list) on CodePen.

コード

<section>
    <div class="section-container">
        <div class="bg content-1">
            <div class="item"></div>
            <div class="item"></div>
            <div class="item"></div>
            <div class="item"></div>
            <div class="item"></div>
            <div class="item"></div>
        </div>
    </div>
</section>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box
}
/* 変数を定義 */
:root {
  --max-width: 1200px;
  --gap: 2rem;
}

.section-container {
  display: grid;
  grid-gap: var(--gap);
  grid-template-columns: 1fr;
  width: 100%;
/* 変数を使用 */
  max-width: var(--max-width);
/* 中央寄せ */
  margin: 0 auto;
}

.bg {
  border: 5px solid rgb(55, 53, 53);
  position: relative;
  opacity: 0.5;
  background-image: radial-gradient(#e331dd 2px, #e5e5f7 2px);
  background-size: 40px 40px;
}

.content-1 {
  width: 100%;
  padding: 2rem;
  display: grid;
  grid-gap: var(--gap);
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 240px);
  justify-content: center;
}

.item {
  width: 100%;
  height: 100%;
  min-height: 240px;
  background: rgba(233, 181, 255, 0.608);
  position: relative;
}

.item::before {
  content: 'item';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: black;
  font-size: 2rem;
}

.item:nth-child(1) {
  grid-column: 1 / 3;
  grid-row: 1 / 3;
}

@media screen and (max-width: 1024px) {
  .content-1 {
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(4, 250px);
  }

  .item:nth-child(1) {
    grid-column: 1 / 4;
    grid-row: 1 / 3;
  }
}

@media screen and (max-width: 764px) {
  .content-1 {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
  }

  .item:nth-child(1) {
    grid-column: auto;
    grid-row: auto;
  }
}