Playing around with this at the moment.

Works after a fashion.

Please change size to suit

Best maybe to keep original ratio size of cell.

So check computed values in Fast Dial/Preferences/General/General/Size

before changing values in code

@namespace url(http://www.w3.org/1999/xhtml);

div.thumbnail:hover
{
width: 480px !important;
height: 360px !important;
}