Use Abbreviated Hex Code

Summary

Shortened Hex Codes gives one digit for red, green, and blue.

Final Code

<style>
  .red-text {
    color: #F00;
  }
  .fuchsia-text {
    color: #F0F;
  }
  .cyan-text {
    color: #0FF;
  }
  .green-text {
    color: #0F0;
  }
</style>

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

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

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

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