I am using firefox version 48 I want to change the default zoom level to 150% without addons, here is what I've tried; I've changed the "site specific" setting to false first I tried changing min zoom to 150, restart, didn't work. It was still set to 150 in about:config but pages weren't zoomed at all. I then reset the minimum zoom to 30 (default) Next I altered layout.css.devPixelsPerPx to 1.0 instead of -1.0, restart, but again the zoom was the same as default, no pages were zoomed in at all. It's still set to 1.0 right now and everything is still at default zoom level. Did I not do this correctly?