Theme-ing graphs?

Is anyone busy with or looking at adding theme functionality to the graphs? They look awful if you are trying/using a dark theme like me.
I dived into the polymer frontend code and find what to change to get the look I wanted (now hardcoded), but it would be nice if we can theme this as well.
I cannot add the var(–blabla) support to the files I need to change.

Some screen snippets of my current state: