In Harlowe, HTML tags (like <img>) and HTML elements (like &sect;) can be inserted straight into your passage text. They are treated very naively - they essentially pass through Harlowe's markup-to-HTML conversion process untouched.

Example usage:

<mark>This is marked text.

&para; So is this.

And this.</mark>

Details:

HTML elements included in this manner are given a data-raw attribute by Harlowe, to distinguish them from elements created via markup.

You can include a <script> tag in your passage to run Javascript code. The code will run as soon as the containing passage code is rendered.

You can also include a <style> tag containing CSS code. The CSS should affect the entire page until the element is removed from the DOM.

Finally, you can also include HTML comments <!-- Comment --> in your code, if you wish to leave reminder messages or explanations about the passage's code to yourself.