Ineffective CSS

Some of the css that i've applied is not effective after I updated my version of hikashop. I am trying to change the size and font color of the product name in the main page. Here is the CSS that i've used:

span.hikashop_product_name{
display:;
margin-bottom:5px;
font-weight:;
color:#f35b00;
font-size:150%;
text-decoration: none;
}

span.hikashop_product_name_mainpage{
font-weight:;
color:#f35b00;
font-size:150%;
text-decoration: none;

}