Un tema gtk3 súper óptimo, antiguamente se encontraba disponible para descargar acá...
/* nautilus-caja-thunar background #786e70 Grapy
jet color in gtk.css (.config/gtk-3.0)
----------------------------------------------
@define-color theme_selected_bg_color #343434;

*:selected{
background-color: @theme_selected_bg_color;
}

*.view:selected {
background-color: @theme_selected_bg_color;
}

textview selection {
background-color: @theme_selected_bg_color;
}

selection {
background-color: @theme_selected_bg_color;
}

menu menuitem:hover,
.menu menuitem:hover {
background-color: @theme_selected_bg_color;
}

switch:checked {
background-color: @theme_selected_bg_color;
}

border-color {
background-color: @theme_selected_bg_color;
}

notebook > header.top > tabs > tab:checked {
box-shadow: inset 0 -3px @theme_selected_bg_color;
}
*/