function toggle(div_id) {
	var el = document.getElementById(div_id);
	if ( el.style.display == 'none' ) {	el.style.display = 'block';}
	else {el.style.display = 'none';}
}

function css_pop(windowname) {
	// set overlay height
	/*if (typeof window.innerWidth != 'undefined') {
		viewportheight = window.innerHeight;
	} else {
		viewportheight = document.documentElement.clientHeight;
	}
	if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
		overlay_height = viewportheight;
	} else {
		if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
			overlay_height = document.body.parentNode.clientHeight;
		} else {
			overlay_height = document.body.parentNode.scrollHeight;
		}
	}*/
	
	if(!window.innerWidth)
	{
		//strict mode
		if(!(document.documentElement.clientWidth == 0))
		{
			viewportheight = document.documentElement.clientHeight;
		}
		//quirks mode
		else
		{
			viewportheight = document.body.clientHeight;
		}
	}
	//w3c
	else
	{
		viewportheight = window.innerHeight;
	}
	
	/*if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
		overlay_height = viewportheight;
	} else {
		if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
			overlay_height = document.body.parentNode.clientHeight;
		} else {
			overlay_height = document.body.parentNode.scrollHeight;
		}
	}*/
	
	if ((viewportheight > document.body.scrollHeight) && (viewportheight > document.body.clientHeight)) {
		overlay_height = viewportheight;
	} else {
		if (document.body.clientHeight > document.body.scrollHeight) {
			overlay_height = document.body.clientHeight;
		} else {
			overlay_height = document.body.scrollHeight;
		}
	}
	
	var overlay = document.getElementById('overlay');
	overlay.style.height = overlay_height + 'px';
	var yOffset
	if (self.pageYOffset){// all except Explorer
	    yOffset = self.pageYOffset;
	}
	else if (document.documentElement && document.documentElement.scrollTop)// Explorer 6 Strict
	{
	    yOffset = document.documentElement.scrollTop;
	}
	else if (document.body){ // all other Explorers
	    yOffset = document.body.scrollTop;
	}
	
	var top = ((viewportheight/2)+yOffset) - 300;
	
	//if resolution is small, the close window link is being cut off. Reset top to move it down.
	if (top < 0) 	
	{
		top = 10+yOffset;
	}
	
	var popupdiv = document.getElementById(windowname);
	popupdiv.style.top = top + 'px';
	
	toggle('overlay');
	toggle(windowname);		
}