I have too many photos on a white background that would require adding your gray background, so I had to change to an all-white background. Then you introduce the problem that images with frames were designed for a colored background.
I have two options:
Change frame color – I could change the frame color to an accent color, if I knew which variable controlled this. Do you have a list of options the color customizer controls?
Eliminate frame – Unlike the Recent Posts element, your Portfolio element does not use frames, so I could match that style, if you tell me where in the code I could make the change.
Let me know what’s easier.