.thumbnail {
	position:relative; /*this is the key*/
    z-index:24; 
    text-decoration:none
}
.thumbnail:hover {
	z-index:25;  TEXT-DECORATION: none
}
.thumbnail SPAN {
	display: none
}
.thumbnail SPAN IMG {
	 BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 2px; PADDING-LEFT: 2px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 2px; PADDING-TOP: 2px; BORDER-RIGHT-WIDTH: 0px
}
.thumbnail:hover SPAN {
	display:block;
    position:absolute;
    top:-15em; left:10em; 
    
    text-align: center
}


<!-- Sample Code for ToolTip -->

/*a.info{
    position:relative; 
    z-index:24; background-color:#ccc;
    color:#000;
    text-decoration:none}

a.info:hover{z-index:25; background-color:#ff0}

a.info span{display: none}

a.info:hover span{ 
    display:block;
    position:absolute;
    top:2em; left:2em; width:15em;
    border:1px solid #0cf;
    background-color:#cff; color:#000;
    text-align: center}*/