Trying to reduce the Padding on the Main Menu CSS not working

Hi, The CSS I am trying to add is not working. I want to reduce the space of the PADDING but it is not effecting it. Am I not adding the correct code? Thanks

#main-menu .navbar .navbar-nav>li>a {
color: #333;
margin: 15px 0;
padding: 0;
border-right: 1px solid #cacaca;
padding: 0 25px;
background: transparent;
}

Also how can I reduce the FONT SIZE of the drop down menu text? TY