Hide navigation pane on certain pages

[Steve887]

I'm trying to hide the side navigation pane but only on certain pages (think for like a login page).

So far the only way I've been able to get close is by setting the OpenPaneLength on the RootNavigation to 0. Which works, but leaves a small margin at the side that I cannot work out how to remove. Is there a better way to do this, or any way to remove the small margin left over?