nav: use Playfair Display 700 for offcanvas nav items (matches footer)

style.css

@@ -2177,6 +2177,8 @@ ul.bookmarks {
 }
 ul.nav .list-group-item a {
   color: #fff;
+  font-family: 'Playfair Display', serif;
+  font-weight: 700;
 }
 ul.nav .list-group-item a:hover {
   color: #25c2a0;