Big map overlay

Hi everyone,
First of all, love the plug-in! But..

Does anyone know how to add an image and/or text on top of the map, as an overlay?

Using CSS for customising the map is awesome, I created a class “mappy”, which I am able to customise through the WP CSS editor (e.g. z-index:-1). Unfortunately I am unable to bring any of the webpage’s context (menu, header, body) to the foreground, and text that I add to the page is nowhere to be seen when I inspect the page in Chrome.

All the best,
Thom

The page I need help with: [log in to see the link]