[roger64]

Originally Posted by Obscured

For highlighting and taking notes with PDFs I use Xodo on my Win 10 laptop.
I cannot find as good an editor for epub/Mobi files; so I have converted a couple of ebooks to PDF via Calibre to use in Xodo.
However the resultant output is not too satisfactory. In Calibre I have adjusted the paper size and base font size several times, but before I drive myself mad, I thought that I'd ask if anyone here has some optimum settings for a 13" screen. I'd be grateful.

This is half a reply. Let's hope it will make you a step closer.

I use the Sigil plugin Prince PDF to convert custom made ePub to six inch (or 9×12cm) PDFs.

You have to download Prince (free for non-commercial use).
You can find an example of the source ePub and target PDF here.

This is the css I use with the plugin.

/*
@font-face {
    font-family: serif;
    src: local("Droid Serif")
}
*/

@page cover { 
  margin: 0 !important; padding:0 !important;				
}

@page {
  size: 9cm 12cm;   /* 14.8cm 19.7cm; */
  margin: 4mm 0mm 4mm 0mm !important;   /* 2.5cm 2.5cm 2.5cm 2.5cm; */
  @top-left {
    font-size: 60%;
    font-style: italic; 
    margin-bottom: 1mm;
    content: string(booktitle);
  }
  @top-center {
    font-size: 60%;
    font-style: italic;
    margin-bottom: 1mm;
    content: string(chaptertitle);
  }
  @top-right {
    font-size: 60%; 
    margin-bottom: 1mm;
    content: normal;
  }
}

@page:first {
  margin: 4mm 0mm 4mm 0mm !important;  /* 2.5cm 2.5cm 2.5cm 2.5cm; */
  @top-left {
    border-width: 0;
    margin: 0;
    content: normal;
  }
  @top-center {
    border-width: 0;
    margin: 0;
    content: normal;
  }
  @top-right {
    border-width: 0;
    margin: 0;
    content: normal;
  }
}

body {
  font-size: 11.5pt;
  font-family: serif;
  text-align: justify;
  hyphens: auto;
}

body.cover {
  page: cover;
}

body div:only-child {
  page: cover;
}

body div:only-child svg {
  height:12cm !important;
}

h1, h2, h3, h4, h5, h6 {
  hyphens: none;
}

div.cover {
  text-align: center;
}

#landmarks {
    display: none;
}