Hello,

I failed to access the admin panel so I will try to help considering on our demo. As you already know you will find the id of the block displayed here: Theme Settings -> Shop -> Promo popups.

Next, please navigate to HTML block as shown here http://prntscr.com/itay6j find your block and check the background of rows and columns as shown here: http://prntscr.com/itaz5h

If you have any further questions please feel free to contact.

Best Regards