Looks good in FF3.0.4/Linux, lines up perfectly all the way down the page. I have no zoom, and I have zoom-text-only turned off. Can't tell which font it is (as I'm not a typeface nerd), but I think I have all the ones listed in font-family installed. But using a background image for those lines could be considered anti-accessibility and anti-readability anyway.

Edit: the sample HTML file gets unaligned after the table, but I think that's because there are some 0.375em paddings scattered around in there (turning those off seem to shore it up nicely).