Servlet to Render a HTML Border Image to Display the Doctype

The servlet shall render the doctype title to an image with a certain width and height to be used in a custom CSS to render a border to the main content of a Confluence page.
Example:

<style>
body.projectdoc-doctype-blank #main
{
  border-image: url('/confluence/plugins/servlet/projectdoc/doctypeBorderImage.png?doctype=blank&height=400') 0 0 0 30 round;
  border-style: inset;
  border-left-width: 30px;
}
</style>