$('body').on('ready resize', 'p.nav > a > span', function(){

var preferredHeight = 800;

var displayHeight = $(window).height();

var percentage = displayHeight / preferredHeight;

var newFontSize = Math.floor(fontsize * percentage) - 1;

$("p.nav > a > span").css("font-size", newFontSize);

});

Why is this code not working

Much Thanks for your help