Firefox Quantum Developer Edition: the fastest Firefox ever with Photon UI and better tooling - Mozilla Hacks - the Web developer blog
Latest Firefox Version Supports Public Key Pinning - Hashed Out by The SSL Store™
This add-on requires a newer version of Firefox (at least version 61.0)" - Why can't I install this add-on, even tough I am using a current Firefox version (66.0.5 on Linux/Fedora)? :
Enter Australis: Mozilla streamlines Firefox's look - CNET
Change look & feel of Firefox pinned tabs
How to Reset/Refresh Chrome and Firefox Quantum Back to Default Settings. (Without Reinstalling)
Windows 10 Help Forums
Customize width of pinned tabs in firefox using Tab Mix Plus - Super User