Firefox: cacher la barre d'onglet / hide tab bar

Copie locale de https://gist.github.com/ruanbekker/f800e098936b27c7cf956c56005fe362, thks https://gist.github.com/ruanbekker

AddOn: https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/

• Go to about:support in your address bar
• Look for your profiles directory and open it:
• Create a file named chrome/userChrome.css in your profile directory:

  mkdir chrome && touch chrome/userChrome.css

Populate the following css code:

#main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar > .toolbar-items {
  opacity: 0;
  pointer-events: none;
}
#main-window:not([tabsintitlebar="true"]) #TabsToolbar {
    visibility: collapse !important;
}
#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
  display: none;
}
.tab {
  margin-left: 1px;
  margin-right: 1px;
 }

Then go to about:config in your address bar and set this to true:

  toolkit.legacyUserProfileCustomizations.stylesheets