I've made some changes and tweaks according to the suggestions that
several people made. Here is a screenshot with the latest changes (on
the right side):
I'm not sure about the dark strokes. They have a lighter outline for
dark themes, but that makes them look blurred.
Removing the outlines and keeping the dark color will make them useless
for dark themes, so there's no way out: It's white with a grey outline
like the original Tango set, or the middle gray with dark strokes
(a.k.a. Bulia's spaghettis :-)
What do you think?