<section class="nth_example">
      <div class="color red">赤</div>
      <div class="color">青</div>
      <div class="color">黄</div>
      <div class="color">緑</div>
      <div class="color red">赤</div>
      <div class="color">青</div>
      <div class="color">黄</div>
      <div class="color">緑</div>
      <div class="color red">赤</div>
      <div class="color">青</div>
    </section>
.nth_example{
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
  padding: 20px;

}

.nth_example .color{
  background-color: #f4f4f4;
  border: 1px solid #ccc;
  padding: 20px;
  text-align: center;
  font-size: 1.2em;
  color: #333;
}

.nth_example :nth-child(2 of .red) {
  background-color: red;
color: #fff;
}

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