/**
 * @author LEC
 */
function centerVertical(elementId, percentOffset){
	try{
		var centerMe = document.getElementById(elementId);
		var centerParent = centerMe.parentNode;
		percentOffset = percentOffset / 100;
		var perfectCenter = ( ( centerParent.offsetHeight - centerMe.offsetHeight ) / 2);
		var topMargin = perfectCenter - (perfectCenter * percentOffset);
		centerMe.style.position = "relative";
		centerMe.style.top = topMargin + "px";
	}catch(err){
		window.alert("error: "+err);
	}
}