@MikeKReader
The cover tool is not intended to be a graphics tool.
It allows you to marry a single image and
current metadata onto a cover blank with ease
You might want to review the HTML section on 'Box Model'
Padding surrounds the inner Block (usually, text or image)
It pushes (spaces) the block away from the
border (may be invisible and tiny, but it is still there)
Margin pushes the
border away from the page edge
Be sure to test on the target device as manufacturers have decided 'We know best'