If you're already dabbling in HTML & CSS, a week of looking at some basic javascript, extension building could give you the same, if not more powerful functionality.
https://help.qlik.com/en-US/sense-developer/May2021/Subsystems/Extensions/Content/Sense_Extensions/e...
As a most basic implementation, an extension with a single text field to paste in your HTML, and a quick bit of code to render that with JS in the paint function ( see link ) would probably work.