So it's doing like you said, the default behavior of wrapping on white space. I remember I ran into this issue on the built-in CSS choices where the preview text or body text would overflow in some cases. I ended up doing this for previews: DIV.first_message { font-size: 75%; width: 80%; text-align:... more
The word break doesn't appear to do anything but I forget CSS stuff constantly so it's there in case I ever want to change it without having to look up things again.