Firefox can zoom in and zoom out on a web pages by pressing Ctrl-+ or Ctrl– keys combination, or by selecting appropriate command in View -> Zoom menu. In Firefox 3, zoom features now magnifies or reduces the size of both text and images.

Beside, zoom function in Firefox 3 also remember the last used zoom level on a domain, and automatically open any web pages from the domain at the zoom level. For example, if you increase the size of text and image on by 1 zoom step, Firefox will remember the zoom level. The next time the reader visits domain or any page from the domain, the page will be displayed at 1 zoom in step.

If you use zoom function just for temporary reading, and would prefer Firefox to display an new pages at normal zoom or default size, regardless of what the page from the domain is displayed on last visit, here’s the trick to hack the Firefox zoom feature.

Type about:config in the Location Bar. Search or filter for browser.zoom.siteSpecific preference name, then double click on the preference to change its value to false (by default is “true”).

Voila, all new pages on Firefox tab or window now get reset to base normal zoom level.