That makes sense about the image size being too big. It's 1035x1600 pixels
Here is the code in the Cover.html page
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>cover</title>
</head>
<body>
<img alt="" height="100%" src="../Images/CoverImage.jpg" width="100%" />
</body>
</html>