Random Changing Background Colour

I appear to have hit upon a random issue where the background colour of the site changes. As I can only find that the background colour is defined in the Sparky values and not the article itself then I am wondering if you can offer any advice
Image attached showing grey and white split even though colour background is set to white

send link

Can link be sent as private message as do no wish to make site address public?

use "Report To Moderator"

If you set Template Style parameter to be one of pre-defined styles then that parameters have no effect. You must use custom style to make the effective

Please explain further?