jQuery Increase Decrease Font Size of Website Dynamically

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>increase or decrease font size of website in asp.net</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js">
</script>
<script type="text/javascript">
$(document).ready(function() {
var divtxt = $('#fontdiv');
 
// Increase Font Size
$('#btnincfont').click(function() {
var curSize = divtxt.css('fontSize');
var newSize = parseInt(curSize.replace("px", "")) + 1;
$(divtxt).css("fontSize", newSize + "px");
});
// Decrease Font Size
$('#btndecfont').click(function() {
var curSize = divtxt.css('fontSize');
var newSize = parseInt(curSize.replace("px", "")) - 1;
$(divtxt).css("fontSize", newSize + "px");
})
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div id="fontdiv">
Welcome to aspdotnetmastersolutions
Welcome to all asp.net solutions with source code
Hi i am winod bhadaliya
</div><br />
<input type="button" id="btnincfont" value=" + " />
<input type="button" id="btndecfont" value=" - " />
</form>
</body>
</html>