When using Ambiance (the default Ubuntu theme), Nautilus 3 has dark breadcrumbs / toolbar (and menu if you disable appmenu), white background and a gray-ish sidebar, which doesn't look too good if you ask me.
In case you're not using Ambiance, here's a screenshot:
In case you're not using Ambiance, here's a screenshot:
Not exactly pretty, isn't it?
So WarriorIng64 has modified Ambiance to use a dark sidebar for Nautilus 3 and in my opinion, it looks a lot better:
Well... what do you think?
If you want to use this modified Ambiance theme, you can download it from HERE. Then, extract the downloaded archive and move the "Ambiance Dark Sidebar" under /usr/share/themes/. Assuming you've downloaded and extracted it in your home folder, use the command below to move it to /usr/share/themes:
sudo mv ~/"Ambiance Dark Sidebar" /usr/share/themes/
And finally, use GNOME Tweak Tool to switch to Ambiance Dark Sidebar. You can also do this without using GNOME Tweak Tool, by using the following command:
gsettings set org.gnome.desktop.interface gtk-theme "Ambiance Dark Sidebar"
Thanks to WarriorIng64 for Ambiance Dark Sidebar; via Barneedhar Vigneshwar & Roland Taylor @ 2buntu