nav-botton issue

I've already successfully used the nav-botton on another site but can't make it work on this one.

I've got nav-botton in the css classes for my donate button.

And this is what is in my Additional CSS:
@media (max-width: 768px) {
.mobile-header-navigation .site-logo.mobile-header-logo img {
height: 108px;
}
.menu-toggle, .main-navigation .mobile-bar-items a {
line-height: 108px;
}
}
@media (max-width: 768px) {
.navigation-branding img, .site-logo.mobile-header-logo {
height: 108px;
}
}

@media (min-width:769px) {
.main-navigation .main-nav ul li.nav-button a {
background-color: #ffffff;
border: 2px solid #000000;
color: #000000;
line-height: 35px; /*this number will likely need to be adjusted*/
}
}

And I've read the instructions and made it work before - I'm stymied.