style.css could not be loaded

After loading page with plug-in "DLF: Page View" there is an 404 - error on the page.
FireBug: "NetworkError: 404 Not Found - http://goobidev.sub.uni-hamburg.de/theme/default/style.css"

The problem is, that in OpenLayers is the property "theme" with the default value "/theme/default/style.css".
The value for "theme" must be "null" to fix the bug.

Viewer.prototype.run = function():

 var options = {
  maxExtent: new OpenLayers.Bounds(0, 0, size_disp.w, size_disp.h),
  controls: [new OpenLayers.Control.Navigation()],
  numZoomLevels: 7,
  fractionalZoom: true
                theme: null
 };