The white border (3 sides, left right and top) is visible in Sigil, Adobe Digital Editions and the Bluefire reader on my Android phone.
The coding for the page itself:
<?xml version="1.0" encoding="utf-8"?>
<!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">
<head>
<title>Cover</title>
</head>
<body>
<div style="text-align: center; padding: 0pt; margin: 0pt;">
<svg xmlns="http://www.w3.org/2000/svg" height="100%" preserveAspectRatio="none meet" version="1.1" viewBox="0 0 625 1000" width="100%" xmlns:xlink="http://www.w3.org/1999/xlink">
<image width="625" height="1000" xlink:href="../Images/cover.jpg"/>
</svg>
</div>
</body>
</html>
And the only other is some bits on the Content.opf
Manifest
<item id="cover.xhtml" href="Text/cover.xhtml" media-type="application/xhtml+xml"/>
Spine toc="ncx"
<itemref idref="cover.xhtml"/>
Guide
<reference type="cover" title="Cover" href="Text/cover.xhtml"/>
thank you!