hi @nolram
I actually see the same issue on Mac in Darkmode in Rhino 7 here. Rhino 7 doesn’t support the automatic color adjustments that Rhino 8 and Rhino WIP have. So this is not something I can fix.
I suggest running your system in Light mode.
Also note that Rhino WIP has a much improved version of Global Edge Continuity. See Rhino WIP Feature: Global Edge Continuity