how to change font using animate?????

Hi in this Link you can find cartbox icon font on a circle, if you rollover then cartbox size gone big and changes it's color

http://www.templatemonster.com/demo/47888.html

I have tried

$(".cartbox-three").mouseover(function(){
// $(this).css('color','#036'); <<< this works but only change color instantly not smoothly
$(this).animate({font:'40', color:'#36'}); <<< this dosen't work
});