my_epub3_template.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:epub="http://www.idpf.org/2007/ops" xml:lang = "{{{lang}}}" lang="{{{lang}}}">
  <head>
    <meta charset = "utf-8" />
    <meta name="generator" content="crowbook" />
    <title>{{chapter_title_raw}}</title>
    <link rel="stylesheet" type="text/css" href="stylesheet.css" />
  </head>
  <body xml:lang="{{{lang}}}" lang="{{{lang}}}">
    <section class = "level1">
      {{{content}}}
    </section>
  </body>
</html>