Disbale Zoom in Iceweasel/Firefox

To access Iceweasel/Firefox's configuration settings, type about:config into the Awesome Bar (URL).

In about:config change:

zoom.maxPercent : 100

zoom.minPercent : 100

toolkit.zoomManager.zoomValues : 1

The Original Values are:

zoom.maxPercent : 300

zoom.minPercent : 30

toolkit.zoomManager.zoomValues : .3,.5,.67,.8,.9,1,1.1,1.2,1.33,1.5,1.7,2,2.4,3

In case you want to turn zoom back on.