There was about a week or when (after clicking on the link in the lower-right corner of the Login page) I got only an error message. Several days ago, the link was fixed, but now we are taken here. Was the old site simply abandoned?
It's the same site, just with a different theme.
Unfortunately, the hoster of the website tried to update the underlying forum software to a new version, which failed and gave the error. After some tinkering it got back to work and now has this new theme, which looks different but is just a slightly different layout and smybols and color scheme.