core middle column background color help

<article class=”col-md-9 col-sm-9″ id=”core_middle_column”> ?? ?????

https://thetravelingdressproject.com/listing/example-listing-1/

I would like to make the right section the same color as the widget box background color. How would I do this in the css?

I want to still be able to see the background image between the widgets and the right section – see attachment mock up. Hope that makes sense.

TIA