Have the address bar and tabs been readable previously? Are you using a theme other than the default theme? You could try starting Firefox in safe mode: https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode You could also try using a new profile: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles You can tweak the address bar height and tab height (and width if that's an issue) using a file called userChrome.css but that is tweaking; you shouldn't have to use that file to make those elements readable. There is also a minimum tab width setting in about:config.

You can set layout.css.devPixelsPerPx to 1.0 (default is -1) on the about:config page. Adjust its value in 0.1 or 0.05 steps (1.1 to enlarge or 0.9 to reduce) until icons or text looks right. Make sure not to use values too large or too small.

• modifying layout.css.devPixelsPerPx affects user interface and webpages (global zoom)

You can open the about:config page via the location/address bar. You can click the button to "Accept the Risk and Continue".

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Firefox has a Zoom section in Options/Preferences to set the default zoom level for webpages.

• Options/Preferences -> General -> Language and Appearance -> Zoom

great..that worked have set tabs add:)ress just right..thank you :)