For HTML documents, however, we recommend that authors specify the background for the BODY element rather than the HTML element. For documents whose root element is an HTML “HTML” element or an XHTML “html” element that has computed values of ‘transparent’ for ‘background-color’ and ‘none’ for ‘background-image’, user agents must instead use the computed value of the background properties from that element’s first HTML “BODY” element or XHTML “body” element child when painting backgrounds for the canvas, and must not paint a background for that child element. Such backgrounds must also be anchored at the same point as they would be if they were painted only for the root element.
I did check that and it is showing that it’s behaving as IE9. I’ve asked someone to have a look to see if there’s anything on the network that might be reporting it differently once it gets off my laptop. The are no issues when I access from here at home, so it’s always possible something’s going on in a proxy or such like.