<div>
  <p class="red">赤</p>
  <p class="green">緑</p>
  <p class="blue">青</p>
</div>
<div>
  <p class="red-a">半透明の赤</p>
  <p class="green-a">半透明の赤</p>
  <p class="blue-a">半透明の赤</p>
</div>
.red{
  color:rgb(255, 0, 0);
}

.green{
  color:rgb(0, 255, 0);
}

.blue{
  color:rgb(0, 0, 255);
}


.red-a{
  color:rgb(255, 0, 0, 0.7);
}

.green-a{
  color:rgb(0, 255, 0, 0.5);
}

.blue-a{
  color:rgb(0, 0, 255, 0.3);
}

External CSS

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External JavaScript

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