function positionMainNav() {
	var navlinks = $$('#mainNav a.level1');
	for (var i=0; i<navlinks.length; i++) {
		// set height according to the design
		var height = 48;
		
		// set correction according to the design when necessary
		var correction = 1;
		
		var elementheight = navlinks[i].getHeight();
		
		var newpadding = (height - elementheight) / 2;
		var newheight = height - newpadding;
		
		navlinks[i].setStyle({
				paddingTop: newpadding + correction + 'px',
				height: newheight - correction + 'px'
		});
	}
}

Event.observe(window, 'load', positionMainNav);