Userscript to move the left-sidebar into the topbar network-wide _{^{( Stack Apps ) ( install ) ( GitHub )}}

Because I really don't like the space wasted by the left-sidebar, I created Left-sidebar in the Topbar, which moves the left-sidebar into the topbar on all SE sites which have the left-sidebar, regardless of the preference set on each individual site. Installing this userscript is equivalent to having selecting a SE network-wide preference to "Hide left navigation". You will not need to set the preference on each individual site.