@ Charles and Steve:
Thanks for your explanations!
So the dark surroundings of the frets are "only" a stylish addition
to the relic look of the fb, but I like it.
But unfortunately you can't hear it...
If I ever get tempted to make a Strat or Tele neck myself,
(I have only made a couple of acoustic guitar necks until now)
I will think about medium-sized frets and also about such dark edges.
Unfortunately, the only thing missing for me now are
the templates for it and the appropriate wood.