Coding seems allright, just depends on what else you want to do in file.
can you try
<div><img alt="cover" src="../Images/cover.jpeg" style="height: 100%" /></div>
or
<div><img alt="cover" src="../Images/cover.jpeg" style="width: 100%" /></div>
replacing your
<div><img alt="cover" src="../Images/cover.jpeg" /></div>
see if there's any difference in how the reader handles the images/zooming.