This is weird. I'm looking at your CSS and the one I'm using right now and the differences I'm seeing are pretty minor. This is what I'm using:

img[src*="user.png"] {
vertical-align: middle !important;
margin: 0 auto;
width: 0 !important;
height: 0 !important;
background: transparent url(http://i.imgur.com/V5uK6Tb.gif) no-repeat;
padding: 0 3px 16px 16px !important;
}

I'm no expert with layout stuff either but maybe try tweaking my code to fit in your details and see if that fixes it?