CSS Layers with z-index

CSS Layers with z-index

I have something like this
<div id="page"> // z-index:1; position:relative;
<div>Some Content</div> // z-index:10000: positon: fixed;
</div>
<div id="mask"></div> // z-index:9998; position:absolute;
<img> // z-index:9999; position: fixed;
I want to display "Some Content" over the picture .
It works if <div id="page"> with z-index:0; and if I change it to
z-index:1; I see the picture but my Content is under it.
How can I put my Content over the picture and still have <div id="page">
with z-index:1;?
As an example see this Link:
http://entw.yogabox.de/Specials/Yogamatten-2-Wahl/Asana-Yoga-Matte-Sticky-lila-2-Wahl.html
You should click the big green button and then you'll see my white picture
without content.