min-width: 0 doesn't work in IE8

[entozoon]

Testing in proper IE8 (document mode IE8 on Windows XP),
respond.js doesn't work with

@media (min-width: 0) { }

However, it works fine with:

@media (min-width: 0px) { }

If that's how it has to be, then fair enough but it did cause me about an hour's worth of head scratching!