DIV overlap in new theme

I have now started to build my German Opencart based on 1.2.4 build. After I inserted my theme, I've noticed it in the admin area only works if I replace the default theme.

Now I also noticed that the modules on the left hand side overlap. In IE6 everything works and all divisions are represented correctly.

In Firefox, the brown area (this is an new DIV with CSS) only goes down if the content area is going larger. Can anyone help me with this strange problem (Gladly in German ).

A live link would be easier to investigate.
Looks like a case of float clearing
Try adding "clear:both" to the css for that brown area.

Sorry but I edit the page offline. That's why I can not post link.

Thanks for your tip with the "clear: both". I totally overlooked. Now I have a small problem.

The background still ends with the content module instead of the modules on the left.
If you are in the CSS file and assign a background on #container field, this area is a logical way up. Then I got this problem quite below the range of about 3-4 pixels lit.
Can I fill the area otherwise than through the container CSS?