Well, I have compiled from sources already... and after cssutils update it works fine.
But to the results: It turned out that Kindle's blog = 0x102 = news feed with flat navigation. Which is certainly less of a problem for me than the broken Kindle behaviour of 0x103 (after all, the next/previous section navigation by arrows is supported by 0x102). So I set Calibre to produce 0x102 instead of 0x103 and I was happy - until I found out that subsequent "blogs" are actually not replaced but all instances are placed to Home, even if exactly the same "blog" is sent repeatedly...
This is rather strange as
1) when I copy over USB, the problem is gone (only one instance is kept)
2) when I receive the subscribed blog from Amazon, one instance is kept
So it seems to be a problem of sending via wifi (I use gmail)... and I have no idea why this is happening...