only in patch2:
unchanged:
--- a/core/themes/bartik/css/components/dropbutton.component.css
+++ b/core/themes/bartik/css/components/dropbutton.component.css
@@ -38,6 +38,10 @@
   background-color: #e8e8e8;
   background-image: -webkit-linear-gradient(top, #e8e8e8, #d2d2d2);
   background-image: linear-gradient(to bottom, #e8e8e8, #d2d2d2);
+  height: 25px;
+  border-top-right-radius: 15px;
+  border-bottom-right-radius: 15px;
+  margin-top: 2px;
 }
 .js .dropbutton-toggle .dropbutton-arrow:hover {
   background: #ccc;