[Craft] {{diagram}} is not in theme

[kvistgaard]

For example, it has the stock background
Also, it's missing as an element for customisation

[rcvd]

This is also a tough one because Roam does not give any CSS classes to the elements of the diagram nor the diagram itself. It's "just" an inline SVG that will be manipulated. I could do some style*= parsing but this is very error-prone.