WhiteSur-gtk-theme/src/sass/gtk/apps/_gnome-40.0.scss

/************
 * Nautilus *
 ************/

 .nautilus-window {
  // Floating Bar
  .floating-bar {
    padding: 2px;
    background-color: $selected_bg_color;
    color: $selected_fg_color;
    border-radius: $wm_radius - $container_padding;
    margin: $container_padding;
    box-shadow: $shadow_5;

    button {
      border: none;
      border-radius: $circular_radius;
      min-height: 0;
      min-width: 0;
      padding: 0;
      margin-right: container_padding;
      -gtk-icon-shadow: none;
      @extend %selected-button;
    }
  }
}

#NautilusViewCell {
  clamp box {
    margin: 0;
    border-spacing: 0;
  }
}

#NautilusQueryEditor { // search entry
  padding: 1px $container_padding;

  > menubutton > button {
    min-width: 16px;
    min-height: 16px;
    margin: 0;
    -gtk-icon-size: 12px;
    padding: 0 4px;
  }

  > text, > image { margin: 0; }
}

#NautilusPathBar {
  background-color: $fill_color;
  border-radius: $bt_radius;
  margin: $container_padding 0 $container_padding $container_padding;

  #NautilusPathButton {
    margin: 0 $container_padding / 2;
    border-radius: $bt_radius;

    &.current-dir {
      color: $header_fg;
  
      &:hover, &:active {
        background: none;
        box-shadow: none;
      }
    }

    &:first-child { margin-left: 0; }
  }

  > menubutton {
    margin-top: 0;
    margin-bottom: 0;
  }
}

// Extensions
window.nightthemeswitcher headerbar {
  background: $header_bg;
  color: $header_fg;
}

//
// Gnome Control Center
//

window.background.csd {
  > contents {
    > leaflet.unfolded > box {
      > headerbar {
        @extend %side_headerbar_left;
      }

      > searchbar {
        @extend %side_searchbar;
      }

      > stack > widget > box > widget > headerbar,
      > stack > widget > overlay > leaflet.folded > box > headerbar {
        @extend %side_headerbar_right;
      }

      > scrolledwindow > viewport > widget > stack {
        > list.navigation-sidebar {
          background-color: rgba($dark_sidebar_bg, 1);

          > separator {
            background-color: transparent;
            margin: 0;
            min-height: 0;
          }
        }

        > box > list.navigation-sidebar { background-color: rgba($dark_sidebar_bg, 1); }
      }

      > stack.background { background-color: $base_color; }
    }
  }
}