The red sliver should be half the width shown.
It’s not drawn to scale and I didn’t draw it. If I had, I would have put the red marker on the Left, where it belongs.
10th Generation takes up 2 arc segments.
You have to look closely, but the two outer rings together comprise the 10th degree of separation; instead of dividing each cell from the ninth into two cells side by side, they made it into two new rings of cells, probably because they couldn’t make the lines that close together. It is confusing, though.