Arc-39-theme/common/gtk-3.0/3.20/sass/_transparent_widgets.scss

//.nemo-window GtkEventBox { background-color: $bg_color; } // fixes nemo statusbar

//.nemo-window,
.nautilus-window {
  paned > separator {
    background-image: _solid($dark_sidebar_border);

    @if $variant=='light' {
      &:dir(ltr) { margin-left: -1px; }
      &:dir(rtl) { margin-right: -1px; }
    }
  }
}

filechooser paned > separator { background-image: _solid($dark_sidebar_border); }

// Dark transparent sidebars
filechooser,
.nautilus-window {

  &.csd.background, placessidebar list { background-color: transparent; }

  placessidebar.sidebar {

    background-color: $dark_sidebar_bg;

    row.sidebar-row {
      border: none;
      color: $dark_sidebar_fg;

      .sidebar-icon { color: transparentize($dark_sidebar_fg, 0.4); }

      &.has-open-popup,
      &:hover { background-color: transparentize($selected_bg_color, 0.75); }

      &:disabled {
        &, label, image { color: transparentize($dark_sidebar_fg, 0.6); }
      }

      &:selected.has-open-popup,
      &:selected, &:selected:hover, &:active:hover {
        @extend %selected_items;

        .sidebar-icon { color: inherit; }
      }

      &:not(:selected) button.sidebar-button {
        color: $dark_sidebar_fg;

        &:hover { @include button(osd-hover); }
        &:active { @include button(active); }

        &:not(:hover):not(:active) > image { opacity: 0.5 };
      }

      &.sidebar-new-bookmark-row {
        color: $selected_bg_color;

        .sidebar-icon { color: inherit; }
      }

      &:drop(active):not(:disabled) {
        &, label, .sidebar-icon { color: $drop_target_color; }

        &:selected {
          &, label, .sidebar-icon { color: $selected_fg_color; }
          background-color: $drop_target_color;
        }
      }
    }

    separator { background-color: transparent; }

    scrollbar { @extend %dark_sidebar_scrollbar }
  }

  &.maximized placessidebar.sidebar { background-color: opacify($dark_sidebar_bg, 1); }
}

.nemo-window {
  .sidebar {
    color: $dark_sidebar_fg;
    background-color: $dark_sidebar_bg;

    .view, row {
      background-color: transparent;
      color: $dark_sidebar_fg;

      &.cell:selected {
        background-color: $selected_bg_color;
        color: $selected_fg_color;
      }

      &.expander {
        color: mix($dark_sidebar_fg, $dark_sidebar_bg, 50%);

        &:hover { color: $dark_sidebar_fg; }
      }
    }

    separator { background-color: transparent; }

    scrollbar { @extend %dark_sidebar_scrollbar }
  }
}

.caja-side-pane {

  &,
  > notebook > stack > widget > box,
  text,
  treeview {
    color: $dark_sidebar_fg;
    caret-color: $dark_sidebar_fg;
    background-color: opacify($dark_sidebar_bg, 1);
  }

  > box button {
    &:not(:active):not(:checked) { color: $dark_sidebar_fg; }
    &:hover:not(:active) { @extend %dark_sidebar_button:hover; }
  }

  .frame { border-color: darken(opacify($dark_sidebar_bg, 1), 5%); }

  scrollbar { @extend %dark_sidebar_scrollbar; }
  junction { background-color: darken($dark_sidebar_bg, 5%); }
}

filechooser {

  actionbar {
    color: $dark_sidebar_fg;
    background-color: $dark_sidebar_bg;
    border-color: if($variant =='light', darken($dark_sidebar_bg, 7%), darken($dark_sidebar_bg, 15%));

    button { @extend %dark_sidebar_button; }
    entry { @extend %dark_sidebar_entry; }

    @extend %osd_check_radio;

    label, combobox { color: $dark_sidebar_fg; }
  }
}

// Gedit
.gedit-bottom-panel-paned { background-color: $base_color; }

.gedit-side-panel-paned > separator { background-image: _solid($dark_sidebar_border); }
.gedit-bottom-panel-paned > separator { background-image: _solid($borders_color); }

.gedit-document-panel {
  background-color: $dark_sidebar_bg;

  .maximized & { background-color: opacify($dark_sidebar_bg, 1); }

  row {
    color: $dark_sidebar_fg;
    background-color: transparentize($dark_sidebar_fg, 1);

    &:hover {
      background-color: transparentize($selected_bg_color, 0.75);
    }
    &:active {
      color: $selected_fg_color;
      background-color: $selected_bg_color;

      button { color: $selected_fg_color; }
    }
    &:selected, &:selected:hover {
      color: $selected_fg_color;
      background-color: $selected_bg_color;
    }
    &:hover:not(:selected) button:active {
      color: $dark_sidebar_fg;
    }
  }
}

%dark_sidebar_button {
  @include button(osd);

  &:hover { @include button(osd-hover); }
  &:active, &:checked { @include button(osd-active); }
  &:disabled { @include button(osd-insensitive); }
}

%dark_sidebar_entry {
  @include entry(osd);

  &:focus { @include entry(osd-focus); }
  &:disabled { @include entry(osd-insensitive); }
}

%dark_sidebar_scrollbar {

  border-color: darken($dark_sidebar_bg, 5%);

  &.overlay-indicator:not(.dragging):not(.hovering) slider {
    background-color: lighten($dark_sidebar_fg, 15%);
    border: 1px solid transparentize(black, 0.7);
  }
  slider {
    background-color: transparentize(lighten($dark_sidebar_fg, 15%), 0.3);

    &:hover { background-color: mix($selected_bg_color, $dark_sidebar_fg, 20%); }

    &:hover:active { background-color: $selected_bg_color; }

    &:disabled {
      background-color: transparent;
    }
  }
  trough {
    background-color: darken($dark_sidebar_bg, 5%);
  }
}