Custom CSS tweaks for Firefox v4.7.5

Full code changes: https://github.com/Aris-t2/CustomCSSforFx/commits/

Changelog:

[Buttons]

• (tweak) buttons on bookmarks toolbar Aero appearance
• (tweak) bookmarks on bookmarks toolbar Aero appearance
• (fix) Fx141+: buttons on bookmarks toolbar > old size and appearance
• (tweak) Fx133-141+: back/forward buttons > connected to location bar

[Tabs]

• (fix) tabs below navigation toolbar
• (fix) Fx141+: tabs multiple lines (thanks to MrOtherGuy)
  • old version is still present for Fx 128-140: tabs_multiple_lines_fx128-140.css

[General UI]

• (tweak) popup compact menus
• (tweak) popup menus space before label
  • renamed '_fx139'file to popup_menus_space_before_label_fx128-139.css for consistency reasons