This is the most correct approach so far. I have a question for you though: does the red line really "pop"?

Yes, you are right, so I increased the line width a little bit... I got some issues in the process though. I dont know why inside 'stroke', d is an Object but inside 'strokeWidth' is an Array of Objects. It seems like de data has been transformed when I use strokeWidth? It's weird... (that's why I use the 'some' method to get any Object of the array)

Yes. I noticed that too —unsure whether it's a Plot bug or an internal feature. What you can do is create two marks: one for the background lines and another one for the top performer. You'd just need to use the filter transform https://observablehq.com/plot/transforms/filter (same condition as you have now d.name === topPerformerName) If you don't want to overcomplicate your code. I really only meant whether black was the right color. But additionally, using an extra channel, like the strokeWidth, makes it even better.

OKei. I got it now, I used that filter transfgormation and it seems to work as expected. I thought that red with black makes a good contrast but I think that with gray it highlights better, or maybe are u saying to use some categorical scale like green for the top, red for the lowest and grey for the rest? Thanks for the feedback!

Nope, that's it! Gray works better.