Remove close button

[Froggy232]

Hello,
First, thanks you a lot for your theme!
I use unite to remove close button, and it only work in firefox if I tick "Titlebar" in customization page.
Problem is, if I tick it colors change slightly, for the worse.
I would like to disable titlebar and manually remove the close button.
Alternatively, I would be happy if I could enable titlebar in customization and keep the same color scheme.
I have tried to add ".titlebar-buttonbox-container{ display:none } " to userChrome.css but it didn't work.
Does someone have an idea?
Thanks you