Yuri Vishnevsky

Try Plot.normalizeY stroke that follows the fill color, something like:
stroke: d => meanAges.get(d.breed) + 2,

Veli

That's interesting! One consequence of doing this is that it changes the colors of the fill, since the domain of the color scale expands to accomodate the extra values from the stroke.

indeed, i tried it now :) makes sense 

BTW i used a similar concept here:
https://observablehq.com/@bagami/slucajevi-po-zupanijama

COVID trends per county (for Croatia)