Can't change background in 'Theme Options'

Hi there,

My site is: https://www.pbandjabbers.com and I am using a child Twenty Eleven theme.

Until about 30 minutes ago, I was able to change the background (that is the outer background, and not where the main text is) on my site in the Appearance > Theme Options menu in the Dashboard. Now, my background has gone from a sandstone color (#C6C085) to a grey and it won’t change to any other color.

Any idea as to why this may be happening? I have not played around with the background color in my child theme so not sure why it’s suddenly stopped working. Any way to override this in my child theme using code?

Thanks in advance for your help.