[DrChiper]

Originally Posted by Sirtel

There is an option in Kobo eReader.conf (.kobo/kobo) on a Kobo that will ignore widows/orphans with epubs. This can be overridden in the CSS. But if you remove all widows and orphans from CSS or set them to 1, this should work.

[Reading]
readingAdobeOrphans=1
readingAdobeWidows=1

Thats a great find

I had recently the same issue, but solved it in the CSS itself, so it also works on other devices:

body {
  font-family: serif;
  margin: 0 1%;
  orphans: 1;
  widows: 1;
}
p, div {
  font-size: 1em;
  text-align: justify;
  orphans: 1;
  widows: 1;
}