You’ll notice in Nemo 1.8 that it now uses a couple of non-standard UI elements. While we did our best to make them fairly theme-neutral, there
will be are some themes out there that they look less than stellar with.
We did our best to make these new elements as fully theme-able as possible, so that theme developers (as well as end-users) could integrate them as tightly as possible with their surrounding elements. All of the pertinent classes are in this file. You can simply copy and paste it into an existing .css file in the theme, or make it a new file, like nemo.css (don’t forget to import it in your gtk-main.css file.)
The first set of classes are for the new breadcrumbs bar – backgrounds, border color, text color, just about everything can be altered here except the ‘pointy end’.
The second set deals with the disk space indicators in the places sidebar, where colors, width, maximum length, end rounding, and padding can be customized.
Hope this is helpful, and it will be neat to see how various authors integrate these new elements into their theme.