Why I don't mess with Firefox betas. Usually their latest "stable" version has enough bugs as it is. That looks like some problem with interpreting the CSS. The text is indeed set to be left aligned, and appears that way in FF 3.6.12 and also in Mozilla and IE.

Imitating Chaucer? Now there's an ambitious sort of project I might actually be stupid enough to try. But not in this story. Getting it rolling the way I want is difficult enough without adding versification. ;D