8-) Root password ?! (1.0.7 / Rapberry Pi Zero)

Hello,

As I want to customize the UI Design, I have to change files from /opt/piratebox/www directory. It doesn't work when I'm logged in as alarm user => I need to connect as root user. But the password "root" for root user doesn't seem to work...

So please ! Can you tell me the root user password ? Thanks for that ^^
Configuration : PirateBox 1.0.7 with ArchLinux on Raspberry Pi Zero