Make next/prev pagination colors more obvious when links enabled/disabled

Author: christopherthielen

assets/_scss/_navigation.scss

@@ -129,7 +129,7 @@
     font-weight: bold;
     text-align: center;
     text-decoration: none;
-    color: mix(#fff, $gray, 25%);
+    color: darken($gray, 7.5%);
     border: 1px solid $light-gray;
     border-radius: $border-radius;