MarketPress Custom.css

Hi,

I have yellow buy now buttons for MarketPress product widgets. They display in yellow on Safari, and later versions of Internet explorer, but grey on Firefox OS 3.6, Firefox 4.0 Windows, etc.
Should I be editing it somewhere else?
I am using Product theme.

a.mp_link_addcart, a.mp_link_buynow {
float: right;
font-family: "Helvetica Neue",Arial,Helvetica,"Nimbus Sans L",sans-serif;
font-weight: bold;
padding: 5px;
-moz-border-radius: 10px;
-khtml-border-radius: 10px;
-webkit-border-radius: 10px;
border-radius: 10px;
text-decoration: none;
background: #ffffcc;
background: -moz-linear-gradient(center bottom , rgb(199, 199, 199) 39%, rgb(230, 230, 230) 67%) repeat scroll 0% 0% transparent;
border: 1px solid ##2B547E;
}

a.mp_link_addcart:hover, a.mp_link_buynow:hover {
float: right;
font-family: "Helvetica Neue",Arial,Helvetica,"Nimbus Sans L",sans-serif;
font-weight: bold;
padding: 5px;
-moz-border-radius: 10px;
-khtml-border-radius: 10px;
-webkit-border-radius: 10px;
border-radius: 10px;
text-decoration: none;
background: #D2B9D3;
border: 1px solid ##2B547E;