Can't Change Navigation Font to Custom Font

Hello,

I've looked around for an answer to my problem, but none of the solutions out there have worked for.

I'm currently using the Fairfield template.

Here is the most recent think I have tried:

 #page-header nav ul a, #mobileNavigation nav a, .folder-toggle, .subnav a, #headerNav nav a{
  font-size: 15px;
  font-family: 'Chisel-Thin-Normal' !important;
  src: url('https://static1.squarespace.com/static/56f7443fb6aa60a67ecca28c/t/5d72794632b2990001694463/1567783238618/Chisel+Thin+Normal.ttf');
}

Thanks for the help!