My bad,i was in a hurry to answer your question and didnt read in detail. I will try as much as i can and hope Tom can help you with the rest.
Currently the image in the body content makes the side bar widgets, the header and footer fill with color which I’d like to turn transparent so you can see the paper texture instead.
Please go to ” Appearance > Customize > Colors > Content Colors ” and remove the “Background” color value.
Have you tried setting a background image under “Content”? I think its this that will appear as a background for your posts and pages content.
Agressively support the kind of work you want to see. Buy it. Talk about it. Review it.