Missing stylesheet

Hello and first of all a happy new year to the whole team,

today i recognized a missing stylesheet: https://www.w3.org/Guide/guide2006..css
so also the design of the site was totally destroyed...

I checked it again about half an hour later and all was fine, just for your information.

Best regards,
Jürgen Frenzel
Editor - Schluesseldienstvergleich
https://www.schluesseldienstvergleich.eu