XF 1.2 How to set up background Image with external Link?

I want to show up this grafik as background image of my forums:


This is my code:

<style type="text/css">
html {overflow-x:hidden}
body { background-position: center top; background-image: url(http://www.soccer-fans.de/upload/Wallpaper_forum_betathome.jpg); background-repeat:no-repeat; }</style>
<a href="http://www.xyz.de" style="width:100%; height:100%; position:fixed; top:0px; left:0px; z-index:0;"></a>
The Problem ist: On the top, the banner is cut in height of the logo.

Second Problem: The Link to latest threads will be overwritten with the Link URL from the Banner above.

Has anyone an idea how i can display it like i want?