Changing the Background colour product page behind product but not whole page

[GS-Web-Design]

I would like to have the highlighted side of the screen on my product page behind the image to be white, and keep the rest of the screen the light grey colour. is this possible?

In summary, 1/3rd of the page to be a different colour.

[GS-Web-Design]

Thank you,

https://df87fa-2.myshopify.com/products/roller-blinds