In short

I think v0.2.1 broke something on markdown styling, fill and stroke on markdown text no longer work as expected. Doesn't work on latest version either.
I reviewed changelog for v0.2.1, and don't think that this is an intended change.

I'm new to D2, so could be just a misundestanding on my part, but could you please check?

Details

PR #460 introduced style.fill and style.stroke for Markdown text in v.0.1.2.
E2E test added in the same PR: d28aed6

Using the above D2 code from the test, I am unable to get expected results on v0.6.3..v0.2.1.
Using v0.2.0 I do get the expected result.

Demonstration

Using the same test input (above) and ELK layout, results by version:
v0.1.2 (feature introduced)

v0.2.0 (feature last observed working)

v0.2.1 (feature stops working)

v0.6.3 (latest version)