Some of your links to https://caddyserver.com/ are relative and not absolute, leading me to https://ferdinand-muetsch.de/caddyserver.com - Something you should consider fixing.

All in all however, I like the look of Caddy. The best bit I feel has been left out though:

"That is why, effective this release, Caddy will automatically serve all live sites over HTTPS without user intervention."

Which I think is just brilliant.