That's a mad span. It shouldn't have the xmlns tag.
Quote:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Title of the document</title>
</head>
|
from
https://www.w3schools.com/tags/att_html_xmlns.asp
A span should set a style or language for a part of a paragraph (or heading). I can't think what use that xmlns="http://www.w3.org/1999/xhtml" tag would be doing there instead of before <head>
However that looks like kepub, which I never bother with as it's proprietary to Kobo and adds a load of spans.
Try replacing all of
<span xmlns="http://www.w3.org/1999/xhtml" (in a copy) with
<span