[SOLVED] Show firefox 57 tab bar on nav-bar hover

Show firefox 57 tab bar on nav-bar hover

I am trying to edit the userChrome.css file to by default hide the tab bar on FF 57 and did it using the following code

#TabsToolbar {
    visibility: collapse !important;
}

and I want the tab bar to be visible only when I hover over the nav-bar i.e. the toolbar which contains the address field, navigation buttons, menu button and the like stuff. So, I did tried the following way.

#nav-bar:hover+#TabsToolbar{
    visibility: visible !important;
    background-color:red !important;
}

I have noted that the hover attribute is not working at all on the #nav-bar because I have noted that even the background color is also not being changed.

Update: In general, css would work like this:

#b
{
visibility: collapse;
}
#a:hover+#b
{
visibility: initial !important;
}

<!DOCTYPE html>
<html>
<body>

<toolbar id="a">div a
	<p>This para</p>
</toolbar>
<toolbar id="b">div b</toolbar>
</body>
</html>

Solution

This worked for me.

#TabsToolbar {
    visibility:collapse;
}

#navigator-toolbox:hover #TabsToolbar{
    visibility: visible !important;
    
}

This works by instead detecting hover on the entire top navbar