rails/guides/assets/stylesheets/epub.css

p { text-indent: 0; }

p, H1, H2, H3, H4, H5, H6, H7, H8, table { margin-top: 1em;}

.pagebreak { page-break-before: always; }
#toc H3 {
  text-indent: 1em;
}
#toc .document {
  text-indent: 2em;
}

img {
  display: block;
  max-width: 100%;
}