Thanks for the feedback!
I agree that sometimes it's a little hard to see the traces.
But instead of changing the color, I just uploaded a new version that lets you make the lines thicker.
In my testing, I found that to make the traces clearer, I'd be curious to hear if you agree.
I increased the default thickness from 1 to 3, and there's a setting now if you'd like to experiment.
Re: changing the color specifically, I'm not sure that changing the color would help that much.
(I can imagine for any color that sometimes it'd be better and sometimes worse, depending on the times on the belt.)
I've also been thinking about if I can show other information with color, like the speed of the belt (to maybe find that one belt you forgot to upgrade a little faster) or how full it is (to see the difference between a belt that's mostly-full vs. fully-packed).
(Just in the last patch I started using color: I stop tracing pipes if the fluid changes, and show the last line in red in that case.)
