Firefox Metro UI Skin Without Titlebar

Here's how to do this:-

You can install like userchrome or userstyle..

Userchrome

1. Move everything from folder:
(...\UserChrome \EN) English
(...\UserChrome \FR)  French
(...\UserChrome \CZ)  Czech

2. To your profile directory:
C:\Users\"your name"\AppData\Roaming\Mozilla\Firefox\Profiles\"your profile"\chrome

Userstyle

1.  Move everything from folder:
(...\ProfileFolder)
2. To your profile directory:
C:\Users\"your name"\AppData\Roaming\Mozilla\Firefox\Profiles\”your profile”

For other languages make sure that your language is enabled and others are disabled in Firefox add-on menu or You can type to Url bar about:addons