Center Navbar in TheFour Theme

Please remove your coming soon plugin.

Woops. Done.

This CSS, I think

.navbar {
   justify-content:initial;
}
.site-navigation {
   width: auto;
   max-width:initial;
   margin: 0 auto;
}

To add CSS:

• If you are using WordPress 4.7 or later, use the “Additional CSS” option in the customizer.
• If your theme has a custom CSS option, use that to add the CSS shown above.
• If not, install the plugin Simple Custom CSS.

Learn to use the Chrome Developer Tools to help you see and test changes to your CSS.

It worked! Thanks so much Steve!