36-use-rgb-to-mix-colors.html

<style>
  .red-text {
    color: rgb(255, 0, 0);
  }

  .orchid-text {
    color: rgb(218, 112, 214);
  }

  .sienna-text {
    color: rgb(160, 82, 45);
  }

  .blue-text {
    color: rgb(0, 0, 255);
  }
</style>

<h1 class="red-text">I am red!</h1>

<h1 class="orchid-text">I am orchid!</h1>

<h1 class="sienna-text">I am sienna!</h1>

<h1 class="blue-text">I am blue!</h1>