How can I conditionally change the nautilus background color?

Solution 1:

Note: These steps won't work for GTK-2.0, which I think Ubuntu 10.04 uses.

Here is how to change the background color of nautilus in general (for GTK-3.0):

1. Find the location of your theme. For me it was /usr/share/themes/Ambiance
2. It is better to copy this folder in ~/.themes and then make changes to it, rather than making changes in the original location.
3. Look for gtk-3.0/apps/nautilus.css in the Ambiance folder.

4. Add these lines at the top of the file:

   NautilusWindow * {background-color: gray;}

5. Restart nautilus, using nautilus -q command to quit nautilus.

6. You will notice that the background color of browser area changes to gray.

Coming back to your original question, I don't think it's possible to theme nautilus based on location because, changing theme requires nautilus to be restarted. (If you are OK with restarting of nautilus, I guess then someone can write a script which can play with css, based on current browser location. But again, I'm not too sure of that.)