[JSWolf]

Originally Posted by DNSB

Jon, it seems to be odd that when I modify the epub in Sigil before sending it to my PW using calibre, it does work. When I modify the book in calibre before sending it to my PW, it has issues. I haven't tried without the media query which may have something to do with the issue. OTOH, dropping the Sigil modified epub on Kindle Preview and sending the dual mobi to my PW works.

I do notice that the CSS in the calibre generated azw3 is in alphabetical order while the CSS in the Kindle Preview generated azw3 is in the same order as appears in the epub other than changing the media query to all.

@media all{
  html {
    margin-left: -50px;
    margin-right: -50px;
    break-inside: avoid !important;
  }
}

body {
  display: block;
  font-size: 1em;
  margin: 0 0 0 0;
  padding: 0 0 0 0;
  text-indent: 0;
  widows: 1;
  orphans: 1;
}

I don't bother to modify the ePub. I add the CSS to the KF8, save it, and then add the soft hyphens via Hyphenate This! and it works.