All hail the Clipboard API

A florid exposition of CSS code lies below sporting a copy button.

.some-box {
  width: 20px;
  height: 20px;
  background: black;
  margin-bottom: 1.5rem;
}

Here lies a HTML code block with copy button.

<div class="box drop3"></div>

Here lies a pre block that does not contain a code element. You can see it does not have a copy button, as expected! Huzzah!

This is a pre block without code.