Adding glassy Facebook-like border around the content area, css media query

Hi, I don’t know if you can help me out with this but here it goes:
I’d like to add a border to the content area of my site.
Basically I’m trying to make it look like this:
https://www.dropbox.com/s/m663f7un9ik2prp/css%20border.png
Is it possible? if so can you help me with the code?
thanks