alt131 - 5:59 am on Jun 2, 2011 (gmt 0)
Hi Luce, not sure where Laura has gone, but there is a background-image set on body. When I said there were images also "holding" the table open, they are hard-coded in with specified px widths, and a rough check of the maths is within the ball-park.
Recalling that where I am there is absolutely no difference in the display on ie/op/winsaf/ff - regardless of version, screen resolution, or viewport width. For sure, at some screen resolution or viewport widths there is/not a scrollbar, but that is consistent across all browsers at that particular resolution/viewport width. I can't reproduce any instance of ff calculating/drawing any elements "wider" at all.
I've also worked through and removed all child elements. The display remains consistent - at no stage did any firefox version differ from any other browser/version at any screen resolution/viewport width.
Of course, other thoughts are box model, different viewport heights and slightly different viewport width calculation that might trigger a scrollbar - but the difference here is much more than a few px.