No background on page

Hi,

Thank you for your Frau theme which is really nice.
However, I have an issue with all the pages I made. They don’t have the big white square with a thin red line as a background… All I have is the background of my website, the one I can set up in the backoffice.

Here is a link to a page of my website : http://www.nospetitspapiers.com/nous-contacter/

Do you have any clue what the problem is ?
For your information, I am using the free Frau theme (v. 1.6.5)

Thank you !