.icon-28 { background-image: url(28.png); display: inline-block; }
.icon-28-0 { background-position: -0px 0; width: 33px; height: 30px; } 
a.icon-28-0:hover { background-position: -0px 30px; width: 33px; height: 30px; } 
.icon-28-1 { background-position: -33px 0; width: 30px; height: 30px; } 
a.icon-28-1:hover { background-position: -33px 30px; width: 30px; height: 30px; }