Here is what the website sayswhen you access it with Safari:

Sorry, but Safari does not yet
support web word-processing.

We have heard loud and clear that many of you really want it to work, and we have discussed the problems with their development teams. In the meantime, please try us on:
Camino: 1.0a1 or higher
FireFox: 1.0.5 or higher
Mozilla: 1.5 or higher
All of these are FREE and easy to download and use.

Its hardly their fault if the browser doesn't support the features they need. I can confirm that it works great in camino.