// Image Hover functions
// A function to move the background image (preloads this way):
function doHover(button)
{
	var theButton = document.getElementById(button);
	if(theButton.className != "nav_active")
		theButton.style.backgroundPosition = "bottom center";
}

// A function to reset the background image
function stopHover(button)
{
	var theButton = document.getElementById(button);
	if(theButton.className != "nav_active")
		theButton.style.backgroundPosition = "top center";
}