<div id="d1">
  <p>idを設定したdivタブ内の要素</p>
</div>
<div>
  <p>id, class 設定なし</p>
</div>
<div class="c1">
  <p>classを設定したdivタブ内の要素</p>
</div>
#d1{
  color:red;
}
.c1{
  color:blue;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.