[katzgrau]

I'd agree, and this is what I was hinting at in my comment as well.

Plain-text readability is paramount. But additionally, we need to be careful as to how visualizations are implemented. The visual characteristics of the final HTML document are really supposed to exist in the domain of the stylesheet applied to it.

The visualization configuration block in OP's example is perilously close, if not guilty, of violating the traditional separation of concerns we expect with Markdown.