ZIM 9.3.0 has a Tag class that lets you overlay HTML and scale and position the HTML. This is through the CreateJS DOMElement but adds some conveniences and scales and positions dynamically. Check it out at https://zimjs.com/explore/tag.html
More video tutorials for ZIM can be found in the http://zimjs.com/learn section under Tutorials including the ZIM Capture and What IZ? series.