How could I do this in CSS?

Head out to http://www.vpweddingsandevents.com. I've altered the CSS in the theme so my body_wrapper_box is:

.body_wraper_box {
      background:#000;
      width:1125px;
      margin:0px auto;
      -webkit-box-shadow:0 0 5px #888;
      box-shadow:0 0 5px #888;
}

What I would love to do, though, is create a situation like what I've got depicted on the screenshot that's attached. Is there an east / elegant way to edit my body_wrapper_box so I have a thick black border that gives the interior of my box a seamless "black" color around the border, but have a white area within for my text?

What do you think?
Screen-Shot-2014-08-13-at-9.22.49-AM.png