Firefox (57) Quantum is NOT COMPATIBLE with Hide Caption Titlebar Plus. Read that again and let it sink in.
Addon devs asked Mozilla to be allowed to port their Addons to Quantum. They said "no". 
Basically, you must choose between HCTP and Firefox.
You can stall until June 2018 by using Firefox 52 ESR instead (uninstall Firefox 57 first).
If you choose HCTP, try Waterfox and PaleMoon. Both will support extensions like HCTP for the foreseeable future.
If you choose Firefox, TELL MOZILLA you want Firefox to do what HCTP did. Be specific!