.gallery_container{
	position: absolute;
	height:650px;
	top: 0px;
	left: 0px;
	width: 850px;
	/*Add a height attribute and set to largest image's height to prevent overlaying*/
}

.thumbnail img{
	border:0px;
	height:100px;
	z-index:10;
}

.thumbnail:hover{
	position:absolute;
  	z-index:999; 
	padding:0; 
	background:none;
}

.thumbnail:hover img{
	position:absolute;
	height:200px;
	border:0;
	border:1px solid white;
	top: -50px;
}