Need code to change only the secondary navigation color.

Site URL: https://www.sullivandesignstudio.com/

I am wanting to change the color of my secondary navigation to white. As you can see, all the navigation is black and I can change the primary navigation (left of logo) to white using the header styles however I cannot do the same to the right because I am using custom CSS. Can someone provide me with custom code that would allow me to change the navigation text to the right of the logo (secondary navigation) without changing it in the site styles? 

Thanks!

Add to Design > Custom CSS

/* Home nav items */
body.homepage div.header-nav-item a {
    color: white !important;
}