ok, I guess there was misunderstanding here. you said above that the body background color should be FFFFFF
that is not so. the default background color is: background-color: #F5F7FA;
when I go to your board I see the forabg color as green.
if you do not see that, then you must have some type of caching going on somewhere.
do you have another browser you can use to check/
I am using firefox and I see the green for the forabg color.
I notice in the post from a long time ago you were having this same problem:
that shows me that for some reason you are not deleting the cookies and/or pulling a fresh page from the server when you refresh your browser etc.
click on the "delete all board cookies" link at the bottom of the page on your board and see what happens.