Highlight.js + CopyButtonPlugin

Add to header:

<link rel="stylesheet" href="/css/highlight-default.min.css">
<link rel="stylesheet" href="/css/highlightjs-copy.min.css">
<script src="/js/highlight.min.js"></script>
<script src="/js/highlightjs-copy.min.js"></script>

<pre><code class="language-php">
<?php
phpinfo();
?>
</code></pre>

Example

<?php
phpinfo();
?>