S4 with Andoird 5.0.1 and  FireFox 41.0.

Using the AirNZ mobile site, buttons don't work. 

If I tap button it changes colour (so the touch is registered), but nothing happens.

If I switch to the desktop version, the problem disappears.  But it's a PITA to use on a phone.

This doesn't seem to happen on any other site.

I have uninstalled and reinstalled Firefox but the problem persists.

Any suggestions?