It seems to me that the innerbonds should always inside the triangle with an atom in 2 corners and the center of the ring in the other, giving the green/green/black triangle in the picture. The pink lines are orthogonal to the outerbonds. It seems logical to place the innerbond parallel to the outerbond.
After working this out in the code it seems like the idea works, the picture shows how the current code shows some molecules.
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The current code can be found on this page.
The distance between the innerbond and outerbond can be easily changed. I think the distance is fine on the left 2 molecules, and a little too high at the right one. What should the default distance be?