Fix border bottom color collapsed replies

app/assets/stylesheets/pages/notes.scss

@@ -84,8 +84,8 @@ $note-form-margin-left: 72px;
   .replies-toggle {
     background-color: $gray-light;
     padding: $gl-padding-8 $gl-padding;
-    border-top: 1px solid $gray-50;
-    border-bottom: 1px solid $gray-50;
+    border-top: 1px solid $gray-100;
+    border-bottom: 1px solid $gray-100;
 
     .collapse-replies-btn:hover {
       color: $blue-600;

changelogs/unreleased/yo-fix-notes-bb.yml

+---
+title: Fix border bottom color collapsed replies
+merge_request: 51871
+author: Yogi (@yo)
+type: fixed