Changing header nav to custom font

I'm trying to change the font of the navigation buttons in my header ("Home", "About", etc.), because I want them to be the custom font I uploaded instead of one of the default Squarespace fonts. My entire website is using my custom font; it's only these navigation buttons at the top that don't match. I tried the following based on google searches and past forum responses:

.Header-nav-item {font-family: 'NATIONALZ';}

But that doesn't work for me. Maybe it's different in 7.1? Does anyone know how to do this?

@tuanphan Any suggestions? I see you've answered this question successfully in the past, but none of that's working for me; it seems like the answer is different now in 7.1. Thanks so much for any help!

.header-nav *, nav.header-menu-nav-list * {
    font-family: tuanhan !important;
}

Thank you so much!! Worked like a charm!