1. No inline javascript.
2. Self-contained / no external resources.

Adhering to these constraints without subtracting from:

1. 🎨 Appearance
2. 🧸 Interactivity

1. Supported visual representations -- what representations provide the best clarity.
2. Encoding that into the diagram:
   1. SVG fill="url(#gradient)" doesn't work across all browsers.
   2. Effort to write it can be high.
3. Provide an abstraction in the data model to reduce effort.