Okay, here's something to try. Please be very careful with your typing on this change because recovering from a typo is a lot of extra work. (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (2) In the filter box, type or paste '''devp''' and pause while the list is filtered ''Firefox should show a single preference named '''layout.css.devPixelsPerPx''' with a value of'' -1.0 ''indicating that Firefox should follow the system text size,'' (3) Double-click the preference to display an editing field, and *carefully* change the value to '''0.8''' (remove the minus sign so the value is a positive zero point eight) then press Enter or click the blue check mark button to save the change. Firefox should adjust the size of everything down by 20%. How do the toolbars and add-on panels look? After that, you probably want to go back to the Settings page and restore the content zoom factor to 100%.