<div id="parent" class="parent">
  Parent
    <div id="outerChild" class="child">
      Outer child
      <div id="innerChild" class="child">
        Inner child
      </div>
    </div>
</div>
.parent {
  font-size: 20px;
}
.child {
  font-size: 1.5em;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.