How to change the font on the "Login" link on my site's navigation title bar?

Site URL: https://fashionabm.squarespace.com/

I wanted our website to have customer accounts and a link to login/register on the navigation bar itself.

Once I enabled customer accounts on the config page, the login link did appear but then the font for it clashes with the rest of the navigation links. 

How do I go about changing the font on the Login link? I read up on some of the support pages but it's not given me any luck. 

This is my first foray into this forum after years of being a lurker. I'd really appreciate your help!

What is access password?

@tuanphan pw: testing123

Add to Home > design > Custom CSS

span.unauth {
    text-transform: uppercase;
}