Border of widgets right side bar

Hi

In my atahualpa 3.4.9. the border of the widgets ( right side bar) and the line between posts( home page) was a little darker . It was ok.

I've just installed atahualpa 3.5.1 and the border of the widgets is soft. I would like that the border be more widther or darker.

I was in ATO--» sidebers widgtes--» sytle widgets and i add border-width: solid; in the widget container but it does not have effect.

thanks