diff --git a/app/assets/stylesheets/common/base/topic-post.scss b/app/assets/stylesheets/common/base/topic-post.scss
index 1a9a4cf73bd..246b4e28d8c 100644
--- a/app/assets/stylesheets/common/base/topic-post.scss
+++ b/app/assets/stylesheets/common/base/topic-post.scss
@@ -870,9 +870,9 @@ a.mention-group {
   border-top: 1px solid $primary-low;
   color: $primary;
   padding: 1em;
-  margin-bottom: 1em;
   max-width: calc(
-    #{$topic-body-width} + #{$topic-avatar-width} - #{$topic-body-width-padding} + 3px
+    #{$topic-body-width} + #{$topic-avatar-width} - #{$topic-body-width-padding} +
+      3px
   );
 
   p {
diff --git a/app/assets/stylesheets/mobile/topic-post.scss b/app/assets/stylesheets/mobile/topic-post.scss
index 69e58dbeee0..831e47b0ddc 100644
--- a/app/assets/stylesheets/mobile/topic-post.scss
+++ b/app/assets/stylesheets/mobile/topic-post.scss
@@ -475,3 +475,7 @@ span.highlighted {
     margin-bottom: 0;
   }
 }
+
+.post-notice {
+  margin-bottom: 1em;
+}
diff --git a/lib/post_creator.rb b/lib/post_creator.rb
index a74f43f030d..2dd11e649db 100644
--- a/lib/post_creator.rb
+++ b/lib/post_creator.rb
@@ -524,7 +524,7 @@ class PostCreator
       @post.custom_fields["post_notice_type"] = "first"
     elsif SiteSetting.returning_users_days > 0 && last_post_time < SiteSetting.returning_users_days.days.ago
       @post.custom_fields["post_notice_type"] = "returning"
-      @post.custom_fields["post_notice_time"] = last_post_time
+      @post.custom_fields["post_notice_time"] = last_post_time.iso8601
     end
   end