Box Shadow On Main Content/container


I'm after a little help. I'm new to using css cart.

I want to add a box shadow box-shadow: 0 0 40px 9px #000; around my main website container/content, however I've tried adding it to the css where I thought it may go but I get the box shadow on every section inside the blocks.

Could someone point me in the right direction on the which part of the css please?

I'm using Cs Cart version 4 basic theme.

Thank you