offset.js

function offset(element, diffInTop, diffInLeft){
	return element.offset(diffInTop, diffInLeft);
};

Object.prototype.offset = function(element, diffInTop, diffInLeft){
	if( typeof diffInLeft == 'undefined' ){diffInLeft = 0;};
	if( typeof diffInTop == 'undefined' ){diffInTop = 0;};
	if( typeof element == 'undefined' ){element = 0;};
	if( this != window ){
		diffInLeft = diffInTop;
		diffInTop = element;
		element = this;
	};
	rectElement = element.getBoundingClientRect();
	rectHtml = document.querySelector('html').getBoundingClientRect();
	return {
		top: rectElement.top + Math.abs(rectHtml.top) + diffInTop,
		left: rectElement.left + Math.abs(rectHtml.left) + diffInLeft
	};
};

error in mac safari...