move variables

src/client/styles/scss/_override-bootstrap-variables.scss

@@ -59,10 +59,5 @@ $input-bg-disabled:              $btn-default-bgcolor;
 //** `<input>` border color
 $input-border:                   $border;
 
-//== Navbar
-$navbar-default-color: #777;
-$navbar-default-bg: #f8f8f8;
-$navbar-default-border: darken($navbar-default-bg, 6.5%);
-
 //== card
 $card-border-radius: 0;

src/client/styles/scss/_variables-bootstrap.scss

@@ -67,3 +67,8 @@ $modal-header-padding-x: 1rem;
 
 //== Alerts
 $alert-border-radius: 0;
+
+//== Navbar(inherit variables of bootstrap3)
+$navbar-default-color: #777;
+$navbar-default-bg: #f8f8f8;
+$navbar-default-border: darken($navbar-default-bg, 6.5%);