message: Fix `sticky-conversation-sidebar` spacing
diff: .rgh-sticky-sidebar {
  position: sticky;
  - top: 60px !important; /* Matches sticky header's height */
  + top: 76px !important; /* Sticky header's height + sidebar item's margin */
  z-index: 1; /* Needed so the backdrop of notification modal is over the other elements in the conversation */
  }
  