$(document).ready(function() {

		// hide homepage text
		$('div.homepage_text').hide();
		
		var navDuration = 150; //time in miliseconds
    var navJumpHeight = '15px';

    $('#main_nav li a span').hover(function() {
        $(this).animate({ top : "-="+navJumpHeight }, navDuration);            
    }, function() {
        $(this).animate({ top : "0" }, navDuration);
    });
      
});