Šupər♂ - 超人
This is the maximum screen space u can use without "full-screening" ur Firefox with F11.
How to do it?
Simple. As most of us know, the Tiny Menu add-on/extension which replaces the standard Firefox menu bar with a tiny menu popup.
After installing this extension, right-click on the menu bar -> Customize, and then drag-drop all unnecessary buttons onto the Customize pop-up.
Select Show "Icons". Tick-mark "Use small buttons".
Then, in the white-space which replaces the Full Menu(File, Edit...) earlier.., drag-drop other buttons and address bar to get this all in the same line (such that the navigation toolbar is empty now). Disable Navigation ToolBar. Voila!!! A space gain of @least 15%.
I would also request you to use the theme IFox Smooth by Radar.250x for best results.
It as simple as that. And very effective. See how much screen space I saved. Normally about 80-70% screen space is taken by all these buttons and the rest. Now I've @least 95% visibility.