CSS Positioning - bottom:0 - problem in IE6
This is sort of a bug as it is not always 1px inside.
If you resize the window you will find that the red line beneath the footer will vanish on every other pixel resize.
This is just the way that IE has chosen to work out the absolute position. Not very accurate, but there it is.
You can get rid of this by setting the bottom:-1px; but this will produce a vertical scroll bar on every other pixel resize.
You can get rid of the scroll bar by using overflow:hidden.
But I would tend to design around this and have colours that will not show this 'fault'