Here is:
And the example:
<!DOCTYPE html>
<html>
<head>
<title>HTML centering</title>
<style type="text/css">
<!--
html, body, #tbl_wrap { height: 100%; width: 100%; padding: 0; margin: 0; }
#td_wrap { vertical-align: middle; text-align: center; }
-->
</style>
</head>
<body>
<table id="tbl_wrap"><tbody><tr><td id="td_wrap">
<!-- START: Anything between these wrapper comment lines will be centered -->
<div style="border: 1px solid black; display: inline-block;">
This content will be centered.
</div>
<!-- END: Anything between these wrapper comment lines will be centered -->
</td></tr></tbody></table>
</body>
</html>
Take a look at the original URL for full info: http://krustev.net/html_center_content.html
You can do whatever you like with this code. The only condition is that any derived work must have a reference to the original author.