Modifying node connection line color in graph view (Traffic Lights theme)

Love the Traffic Lights theme and I’ve done some customization to suit my tastes.
But I’m having a tough time getting the node connection lines of the graph view to show when the theme is in dark mode. Is there a way I can modify the color? I’ve scrubbed the CSS and can’t find it. Here’s the color CSS right now.

Thanks in advance.