TimelineQueueButtonHeader: improve spacing

app/styles/components/timeline-queue-header.scss

@@ -5,7 +5,8 @@
   max-height: 30px;
   position: sticky;
   top: 60px;
-  margin: 8px auto;
+  margin: 0 auto;
+  margin-bottom: 8px;
   background-color: var(--brand-color);
   color: #fff;
   border-bottom: 1px solid;
@@ -28,6 +29,7 @@
     max-height: 0;
     opacity: 0;
     margin: 0;
+    border: 0;
   }
 
   &__btn {