http://www.pestujemeweb.cz/obsah/hotova-reseni/zmena-obrazku-pri-najeti.php

#block-block-13 .content a { display:block; width:105px;height:37px;overflow:hidden;}  
#block-block-13 .content a img { width:210px;height:37px;border: none; }
#block-block-13 .content a:hover {text-indent: -105px;}