Get content div to hit bottom of the page

On http://audioaffair.co.uk why does the content div #pageSurround not hit the bottom of the browser window when there is sufficient content? (the black background shows through at the bottom even though all margins are 0px. So why does the body end early?)

On pages with less content like (https://www.audioaffair.co.uk/cart.php?act=cart) how can I get the #pageSurround div to hi开发者_高级运维t the bottom of the browser window.

As to your first problem: that is because in CSS there is

.clearfix:after {
content: ".";
    /* ... */
}

So there's a dot between your pageSurround div (with clearfix class) and the bottom of the page.

As to your second problem: the link that trevor posted should help you.