How to center the Firefox #urlbar?

Question

In the Firefox navigationbar I only have the back/forward buttons on the one side
and the menu button on the other side of the urlbar.
Now I'd like to horizontally center the urlbar on the remaining space of the navigationbar with a custom userstyle.

In my css, I've added the following code:

#urlbar {
 width: 800px;
 margin: 0 auto !important;
}

But that doesn't work. Can you maybe point me in the right direction?

Thanks!

Answer 1

I think this is the right way to make the urlbar a fixed width (it's how I have set it on my profile):

#urlbar, #urlbar-container {
min-width: 250px !important;
max-width: 550px !important;
}

Don't know how to make the urlbar centered in the navbar through userchrome.css, but you can achieve the same result with Classic Theme Restorer Extension (or any other that lets you customize the navbar with flexible spaces).