JQ: Change Size On Key Up

HTML

<input type="text" id="my_input">px
<br><br>
<div id="my_div">Hi, I'm A Nice Dive , Change My Size Please</div>

CSS

* {font-family:Segoe UI Light;}

JavaScript

$(document).ready(function(){
    $("#my_input").keyup(function(){
        $("#my_div").css("font-size", $(this).val()+"px");        
    });
});