Twenty ten widget style question

I’m using a twenty ten child theme and i’m trying to make my widgets look like. https://wpaustin.com/child-themes/

so far I have
.widget-title {border: 1px solid #ddd; background-color: #eee; padding: 2px; text-align: center;

which makes makes the title look ok, but when I try to add a border to each widget content, it wraps all the widgets in a border together.
I’ve tried widget-area, and widget-area ul, but can’t seem to get it to look how I want. is there another class I can use for this?

My site is https://zeaks.org