css background color

[InsertName]

I'm trying to add a black background #000000 to a xml xhtml 1.0 strict page but it won't work, only the parts with content is black while the rest is all white but when I removed the xml tag <?xml version="1.0" encoding="gb2312"?> it makes the entire page black

body{
color:#FFFFFF;
background:#000000;
}

any suggestions? or is this just not possible?

[Schmoopy]

A link to the site, or the exact code would be appreciated.

[bluewalrus]

html, body {
height:100%;
everything else you have in body tag
} This might do it if not a link or all of your code