a#pc {
	display: block;
	width: 100px;
    height: 100px;
    background-image: url(images/pc.jpg);
    background-position: 0 0;
    margin: 0 0 4px 4px;
}
a#pc:hover {
    background-position: 0 -100px;
}
a#network {
	display: block;
	width: 100px;
    height: 100px;
    background-image: url(images/network.jpg);
    background-position: 0 0;
    margin: 0 0 4px 4px;
}
a#network:hover {
    background-position: 0 -100px;
}
a#website {
	display: block;
	width: 100px;
    height: 100px;
    background-image: url(images/website.jpg);
    background-position: 0 0;
    margin: 0 0 4px 4px;
}
a#website:hover {
    background-position: 0 -100px;
}
a#spacer {
	display: block;
	width: 100px;
    height: 100px;
    background-image: url(images/spacer.gif);
    background-position: 0 0;
    margin: 0 0 4px 4px;
}
a#spacer:hover {
    background-position: 0 -100px;
}