Hide Tab Bar CSS Alternative

[rehanzo]

Hey, thanks for this project. It is very well done.

On my system, the hide tab bar CSS from the optional CSS mods does not work well. It seemingly just cuts off the top half of the tab bar. However, the following works perfectly for me:

#TabsToolbar {
    visibility: collapse;                                                                 
} 

Maybe you could add it as an alternative in the CSS mods folder, for those that cannot get the current hide tab bar CSS to work right.