Fix for menus margins

libublsettingsui-gtk3.glade

@@ -153,6 +153,9 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
         </style>
       </object>
     </child>
+    <style>
+      <class name="thin"/>
+    </style>
   </object>
   <object class="GtkMenu" id="menu2">
     <property name="visible">True</property>
@@ -197,6 +200,9 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
         </style>
       </object>
     </child>
+    <style>
+      <class name="thin"/>
+    </style>
   </object>
   <object class="GtkWindow" id="MainWindow">
     <property name="width-request">800</property>