#onas {
background-image: url(images/index_03.jpg);
width: 66px;
height: 61px;
display: block;
}

#onas:hover {
background-image: url(images/indexa_03.jpg);
width: 66px;
height: 61px;
}
#onas span {display:none}

#oferta {
background-image: url(images/index_04.jpg);
width: 74px;
height: 61px;
display: block;
}

#oferta:hover {
background-image: url(images/indexa_04.jpg);
width: 74px;
height: 61px;
}
#oferta span {display:none}

#portfolio {
background-image: url(images/index_05.jpg);
width: 99px;
height: 61px;
display: block;
}

#portfolio:hover {
background-image: url(images/indexa_05.jpg);
width: 99px;
height: 61px;
}
#portfolio span {display:none}
#kontakt {
background-image: url(images/index_06.jpg);
width: 78px;
height: 61px;
display: block;
}

#kontakt:hover {
background-image: url(images/indexa_06.jpg);
width: 78px;
height: 61px;
}
#kontakt span {display:none}