As usual... once I ask something, I find the answer (well, at least I think I've found it):
For some reason, my class file has the "font.wordsperline.margin.list" repeated twice.
The first time it appears, it does as in the example by sprite7, like this (original file, not modified yet):
Of course, that was the section I modified, because it was the first I found, and I didn't imagine it could be repeated later in the same file. But it is. This is what I have found now, near the end of the class file:
Why twice? No idea, but it seems that those numbers (150, 100, 50) are the ones that my kindle is using for the margins, not the previous ones. I cannot try just now (I haven't the kindle with me at this moment), but I will try to change those figures... and cross my fingers
