#main {background:url(images/freski_bg.jpg)}

.right13 {background:url(images/svetilniki_interiernie_i_ulichnie_bg.jpg)}
.right14 {background:url(images/tochechnij_svet_bg.jpg)}
.right15 {background:url(images/elektroustanovochnoe_oborudovanie_bg.jpg)}

.left13:hover+.right13 {display:block}
.left14:hover+.right14 {display:block}
.left15:hover+.right15 {display:block}