andi wrote
I don't think you have any CSS control over the contents of the iframe and there are no mechanisms to influence the CSS on the export itself.
To control the CSS of the export: Create your own template, style it by CSS as desired and assign it by the Loadskin plugin to the page you want to export.
Live demo:
http://dw-livedemos.informantum.de/doku.php?id=livedemos:iframe-test2
(The template of the DokuWiki web page shown in the IFRAME of the demo is assigned by the Loadskin plugin.)
HTH - Michael Sy.