function fontSizeToPx(sFontSize) {
		switch (sFontSize) {
			case "small": return "13px";
			case "medium": return "16px";
			case "large": return "18px";
			case "x-large": return "24px";
			default: return sFontSize;
		}
	}
converts a textual font-size value to its px representation
@param {string} sFontSize a string based font-size
@return {string} the px font-size value