These defaults should likely be relocated to ctor here:

https://github.com/twitter/ambrose/blob/master/common/src/main/resources/web/js/modules/ambrose/view/graph.js#L82

Or, perhaps the max width should be derived from default node radius, defined here:

https://github.com/twitter/ambrose/blob/master/common/src/main/resources/web/js/modules/ambrose/view/graph.js#L84