Menu 'border-right: none' not working

I have added menu separators on this page http://79.170.40.241/refthecoffeefactory.co.uk/home

I have also added the following to remove the boarder on the far right of the menu, although it doesn't seem to work.....

#navigation ul.nav > li.menu-item-56 {
    border-right: none !important;

}

Any ideas as to why?