.stars{
    width: 30px;
    height: 30px;
    display: block;
    background: url("stars.png");
    float: left;
}

.activeStar{
    width: 30px;
    height: 30px;
    display: block;
    background-image: url("stars.png");
    background-position: 0 57px;
    float: left;
}