Nav bar button border

Hi

I am using the ReadyReview theme on my site https://www.cricketbagreviews.com

I recently updated the color of my nav bar with help from a user here using the custom css

.nav {
background: none !important;

}
.prenav{
background-color : your desired background color;
}

Unfortunately now the buttoms on my nav bar have a black border on one side. Would anyone be helpful enough to provide a solution?

Thanks

Chris