Saving as "Webarchiv" (german) doesn't work with images

Hi!

I want to save a site as "Webarchiv", but as soon as I open it off-line pictures
are missing, CSS Styles don't work. The site doesn't look as it should.

Any idea? What am I doing wrong? Saving it as "Source" isn't what I want.

Latest Safari-update is installed.

Thanks!