It only happens in a few websites (i.e. http://www.tuxfeed.it/ ) and
in debian sid only, lenny is ok. The webpage is a little messy with
frames and decorations out of place. Zooming charachters in or out
(ctrl + ctrl -) fixes the problem but using default size (ctrl 0)
rendering is wrong. On lenny the page is always displayed correctly.
At first I thought the page was bad coded but on lenny it's ok. Then I
thought it could be a buggy iceweasel version, but lenny had the same
version (not now, ok). Then I disabled extensions and uninstalled
msttcorefonts but again with no success.
So could some of you using sid test the above webpage, maybe zooming
in and out, and confirm my problem? Do you have some hints?