[sunflowerdeath]

It looks strange to me that it tries to use HTML, because then it should be compatible with Web APIs and should render the same. Then it would be basically a browser, not very different from what is used today in Electron. But if it will differ from Web platform, why not to just make lightweight alternative DOM-like API.

[formerly_proven]

Been there, done that. Qt has had a renderer for a reasonable subset of HTML4 and CSS2 since the Qt 3(?) days. If you see a Qt app and there's colored text or bold/italics inside a label or editor, that's all done using that flavor of HTML. It gets rendered through the standard QPainter engine.