I just noticed this. Mozilla/Linux is regularly auto sizing my HTML page. I only noticed this because I was testing Cufon text replacement. There were all these strange artefacts around the type. I thought to scale the page to test if the type was effected by zoom. When I returned the page to 100% the artefacts were gone. Thus the page loads at a scale other than 100%.
I did a search: Moz/Firefox auto size page in browser html stop
Close a few times but no exact matches.
So. Anyone know of this buggy behavior?
I'd recommend searching through a list of reported bugs on Mozillas site, though for FF for linux, I've never heard of this :).
Worst comes to worse, I'd report the bug and see what comes of it