Increase the font size in the FF57 toolbars and menus
Global Zoom Factor
This will enlarge both the toolbar area and the content area:
(1) In a new tab, type or paste
about:config in the address bar and press Enter. Click the button accepting the risk.
(2) In the filter box, type or paste pix and pause while the list is filtered
(3) Double-click layout.css.devPixelsPerPx and change its value to
1.25 and click OK, which corresponds to 125% font size in Windows display settings. The toolbar area should enlarge after a few moments. Too small? Try
1.5 and see whether that suits you better. And so on. If you are on Mac and use a Retina display, anything below
2.0 may be smaller than what you started with, so start with
Important: Do not go below 1.0 because it may become too tiny to edit.