Enter "about:support" as URL and select the "Open containing folder" button. You can reach it using Menu "Help" -> "Troubleshooting Information", too:
MacOS default path: ${HOME}/Library/Application Support/Firefox/
open -a "Helium" --args --make-default-browser && open http://perdu.comPour régler une télécommande universelle (5€ chez Action) pour une TV GRANDIN LD224GTB: