Add the Contra (Konami) code to any website.

All you have to do is include the contra.js script:

<script src="contra.js" type="text/javascript" charset="utf-8"></script>

You can either react based on css styles:

<style type="text/css" media="screen">
  body.contra div.foo {
    /* Awesome style here */
  }
</style>

Or you can add your own javascript handlers and the possibilities are endless:

Contra.addHandler(function() {
  // Awesome things here
});