$(document).ready(function() {  

	var animationDuration = 500; //time in miliseconds
	var distance = "25px";

	$('.menu li a').hover(function() {
		$(this).animate({ height : "+="+distance }, animationDuration);            
	}, function() {
		$(this).animate({ height : "-="+distance }, animationDuration);
	});

	
});