message: Allow side nav borders to extend to left and right edges.
  fix Bug
diff: @@ -5,7 +5,7 @@ $co-m-horizontal-nav__menu-item-link-padding-lr: ($grid-gutter-width / 2);
  display: flex;
  flex-shrink: 0; // prevent collapse of tabs
  list-style: none;
  - margin: 0 !important;
  + margin: 0;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0;
  