a#gpx:link, a#gpx:active, a#gpx:visited {
    display: block;
    width: 48px;
    height: 48px;
    background-image: url('img/gpx-button.png');
    background-repeat: no-repeat;
}	
a#gpx:hover {
    background-position: -48px;
}

a#boot:link, a#boot:active, a#boot:visited {
    display: block;
    width: 48px;
    height: 42px;
    background-image: url('img/boot-button.png');
    background-repeat: no-repeat;
}	
a#boot:hover {
    background-position: -48px;
}