Additional Information: I could find out, that the issue was caused by an affiliate banner (despite being https). Once I removed this the site was “secure” again, so all good.
But the other question, whether the .js and .css files are update with the new photographer Theme to “https” remains open.
thanks for the fast reply. Unfortunately this does not answer my question. I know what mixed content is and yes, this is the problem.
However, the problem is not caused by the content I entered but as it looks by the template itself, specifically the galleries, building on “.js” and “.css” files, where the http:// is hard coded.
I did a check of the site (www.aboutphototravel.de) and all errors popping up come from the standard template files.
I have not installed the latest template update, but does this fix it or is there another way of fixing it but going through each and every -js/.css file, which would be a lot of work.