View file imageupload/adm/style/css/acp_imageupload.css

.imageupload-preview {
	position: relative;
	display: inline-block;
	width: 20px;
	height: 20px;
	margin-bottom: 2px;
	vertical-align: middle;
}

.imageupload-preview img {
	position: absolute;
	-moz-transition: all 1s ease;
	-webkit-transition: all 1s ease;
	left: 0px;
	top: 0px;
	max-height: 20px;
	max-width: 20px;
}

.imageupload-preview img:hover {
	max-height: 550px;
	max-width: 550px;
	box-shadow: 0 0 20px #000;
	z-index: 10;
}