problem with ie8

hi.
I would like to decrease the distance between the menu and the font size.

i changed in style.cc

#mainmenu li a {
display:block;
text-decoration:none;
padding:12px 20px;
font-size:14px;
font-family:'OpenSansbold';
text-transform:none;
color:#fff;

in
#mainmenu li a {
display:block;
text-decoration:none;
padding:12px 8px;
font-size:12px;
font-family:'OpenSansbold';
text-transform:none;
color:#fff;

it work with chrome an ie10, but not with ie8..
can you help me?
thank you very much

ok, i fund. i must change also ie.css