.popup{
position: relative;
z-index: 0;
}

.popup:hover{
background-color: transparent;
z-index: 50;
}

.popup span{ /*CSS for popup window*/
position: absolute;
background-color: #ffffff;
background-image:url(http://g.mwsrv.com/images/formbg.gif);
background-position:top center;
background-repeat:no-repeat;
padding: 5px;
left: -100px;
top: -10px;
border: 1px dotted;
visibility: hidden;
color: black;
text-decoration: none;
}

.popup:hover span{ /*CSS for popup window on hover*/
visibility: visible;
top: 0px;
left: -500px; /*position where the popup window should offset horizontally */

}