Recently i decided to move the gnome shell due the unity being more memory hungry (still not greedy as windows) and slow. Gnome shell was fast for me and responsive that unity. So when i moved to Ubuntu Gnome Remix the default browser was Epiphany. I love the look and feel of it and the maximize mode which removes the titlebars to get more space. But still i miss firefox due to the add-ons I'm used to. So here comes the search for firefox add-on to make it look like Epiphany. i found the following add-ons which did the trick.
Above Gnome 3 add-on will make your firefox looks more like a gnome 3 application with Adwaita theme.
Above will hide titlebars when you maximize firefox.
Thanks for generous people who contribute on making those two plugins.