function showModal(modalID){ prepare('100%', 'hidden', 'block', modalID);}
function hideModal(modalID){ prepare('auto', 'auto', 'none', modalID);}

function prepare(height, overflow, display, modalID){
		bod = document.getElementsByTagName('body')[0];
		bod.style.height = height;
		bod.style.overflow = overflow;
		
  
		htm = document.getElementsByTagName('html')[0];
		htm.style.height = height;
		htm.style.overflow = 'scroll';
		
		document.getElementById("blackout").style.display = display;
		document.getElementById(modalID).style.display = display;
	}