On Windows/Chrome, the left panel holding the diagram specification renders at about 150px wide, so it's really hard to read.

Bigger picture, I think declarative diagrams are great. I do think beyond the challenge in getting a specification for a diagram to line up with a specification of a system in some domain, there's the challenge to support many flavors of system specification over a common diagramming substrate, and that that will be an important problem for you to solve.