Case breaks things; entering a sub-domain name with uppercase letters causes the local server to fail. DNS names are supposed to be case-insensitive.

http://www.rfc-archive.org/getrfc.php?rfc=4343

is that the fault of DNS or the actual server sitting behind it, expecting the host header?

It's the fault of the server reading the host header. I'll fix it now.

Cool. It normalizes to lowercase, but it's otherwise functional, even if the URL bar's case differs from the posted version.