I've been building a tiny Markdown browser a) in my language that translates statements 1:1 to machine code, and b) with thorough unit tests for all the rendering logic without any external dependencies: https://github.com/akkartik/mu/tree/main/apps/browse

Here's a screenshot from http://akkartik.github.io/mu/html/apps/browse/main.mu.html#L81

More details on the project: https://github.com/akkartik/mu