Fix padding/alignment of gr-button gr-message

Change-Id: Ibedbc5f1f12f46069f216be59c176772b4d57004
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.html b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
index e04eeb7..5a47dbc 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.html
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
@@ -93,6 +93,12 @@
       gr-account-chip {
         display: inline;
       }
+      gr-button {
+        --gr-button: {
+          padding-left: 0;
+          padding-right: 0;
+        }
+      }
       .collapsed gr-comment-list,
       .collapsed .replyContainer,
       .collapsed .hideOnCollapsed,