Hi skycor,
I do not know ponder stibbons (use DokuWiki since 2-3 years now) but I tested embedding HTML.
It works if I write the following:
This is some <html><span style="color:red;">inline HTML</span></html>.
That gives me a red text-color for "inline HTML".
Also make sure that in the configuration under section "Editing", the option "htmlok"/"Allow embedded HTML" is set. Default is not set.
Kind Regards,
Lars