I did but this is not so good sulotion because you can’t control the opacity of the border by it’s own. The border sits on top of the content area and its transparensy depends on the transparensy of the content area so I can’t make just the border transparent.
Is there a way to ask the developers to add these feature? It seems that the ability slipped in the development process because the developers referred to the control of the radius on the content area (which includes the border) as you can see in the picture I attached.