The Navbar isnt inside the custom.css part. You can change the default navbar in the bootstrap.min.css or add a class in your custom.css and add that class to your navbar in your navbar.tpl.
Both ways work I would recommend creating a new class.
~Tsuki
Tsuki · over 6 years ago
· Last edited: over 6 years ago
You can paste that into styles/themes/theme/css/custom.css. However, to view the changes, you may need to force a cache refresh by pressing Ctrl+F5 in your browser whilst viewing your site.