I'm not sure whether the problem is the content is huge, or everything is huge, or the Firefox window frame goes off the screen.

• First make sure you're not in Firefox's "full screen" view. You can use the F11 key on the keyboard to switch between regular and full screen mode.

• For huge content, try using zoom. Hold down the Ctrl key and tap the - key to shrink it. To enlarge again, hold down the Ctrl key and tap the + key.

• If everything is huge, could you check the shortcut you use to start Firefox, and make sure it doesn't have any size setting on the Compatibility tab? It's best to leave everything unselected on that tab. (right-click the icon > Properties > Compatibility)

(If that doesn't help, there is an internal Firefox setting that might need to be adjusted, but let's come back to that.)

• For an oversized window, you can try using this old-fashioned keyboard method:

Press Alt+Spacebar to open the window control menu, then press S or click Size, press the down arrow once, then up arrow until the bottom of the window comes into view. Press Enter to finish. Repeat with the right side (right once, then left repeatedly).

Does any of that help?

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB

You can check for problems caused by a corrupted localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

If all elements on the Firefox screen look larger then try these suggestions:

You can set the layout.css.devPixelsPerPx pref on the about:config page to 1.0 or on Windows 8 to 1.25 and if necessary adjust layout.css.devPixelsPerPx starting from 1.0 in 0.1 or 0.05 steps (1.1 or 0.9) to make icons show correctly.

• http://kb.mozillazine.org/about:config

See also:

• https://support.mozilla.org/kb/forum-response-Zoom-feature-on-Firefox-22

Use an extension to adjust the text size in the user interface and the page zoom in the browser window.

You can look at this extension to adjust the font size for the user interface.

• Theme Font & Size Changer: https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

You can look at the Default FullZoom Level or NoScript extension if web pages need to be adjusted after changing layout.css.devPixelsPerPx.

• Default FullZoom Level: https://addons.mozilla.org/firefox/addon/default-fullzoom-level/
• NoSquint: https://addons.mozilla.org/firefox/addon/nosquint/