A simple subnet calculator that will accept either an IPv4 or IPv6 subnet in CIDR notation

For example or beef::/112 is acceptable.  The tool (should) automatically detect the IP version and output accordingly (broadcast for v4 etc). It will output info like first/last usable and number of usable hosts in the subnet.

The aim was mostly to avoid any drop down boxes or radio buttons to make it as easy (and quick!) to use as possible.

Any comments or suggestions are welcome :)