change default link-color

packages/preset-themes/src/styles/mono-blue.scss

@@ -21,7 +21,7 @@
 
   $body-emphasis-color:       black;
 
-  $link-color:                $primary;
+  $link-color:                $gray-800;
 
   @import 'bootstrap/scss/variables';
   @import 'bootstrap/scss/variables-dark';