Navigation Borders

Is there a way to change the nav borders. I'd like them to be white if possible? I've tried a few things in the custom CSS box but I don't think I have the correct object in my command. Do you know the correct code? Here's what I have. #header-menu-container { border-style: solid; border-color: #ffffff; } Thanks for any help you can provide. Best, Graham media-cracker.com