Fix disabled Tab css

Author: Dave Conway-Jones

nodes/ui_base.html

@@ -2,7 +2,7 @@
     :root {
         --nr-db-dark-text: #444;
         --nr-db-light-text: #eeeeee;
-        --nr-db-disabled-text-grey: #999;
+        --nr-db-disabled-text: #999;
     }
     .nr-db-sb {
         position: absolute;