paper-gtk-theme/Paper/gtk-3.20/widgets/_base-states.scss

/***************
 * Base States *
 ***************/
.background {
  color: $fg_color;
  background-color: $bg_color;

  &:backdrop {
    color: $backdrop_fg_color;
    background-color: $backdrop_bg_color;
    text-shadow: none;
    -gtk-icon-shadow: none;
  }
}

/*
   These wildcard seems unavoidable, need to investigate.
   Wildcards are bad and troublesome, use them with care,
   or better, just don't.
   Everytime a wildcard is used a kitten dies, painfully.
*/

*:disabled { -gtk-icon-effect: dim; }

.gtkstyle-fallback {
  color: $fg_color;
  background-color: $bg_color;

  &:hover {
    color: $fg_color;
    background-color: lighten($bg_color, 10%);
  }

  &:active {
    color: $fg_color;
    background-color: darken($bg_color, 10%);
  }

  &:disabled {
    color: $insensitive_fg_color;
    background-color: $insensitive_bg_color;
  }

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

.view,
%view {
  color: $text_color;
  background-color: $base_color;

  &:backdrop {
    color: $backdrop_text_color;
    background-color: $backdrop_base_color;
  }

  &:selected {
    &:focus, & {
      @extend %selected_items;

      border-radius: 3px;
    }
  }
}

GtkTextView,
textview {
  text {
    @extend %view;

    selection { &:focus, & { @extend %selected_items; }}
  }
}

GtkTextView,
textview border {
  background-color: mix($bg_color, $base_color, 50%);
  background-image: image(transparentize(black, 0.8)); // HACK: the border node just draws background so,
  background-repeat: no-repeat;                        // using a background-image to draw the border

  &:backdrop { background-color: mix($backdrop_bg_color, $backdrop_base_color, 50%); }

  &.bottom {
    background-size: 100% 1px;
    background-position: top;
  }

  &.top {
    background-size: 100% 1px;
    background-position: bottom;
  }

  &.left {
    background-size: 1px 100%;
    background-position: right;
  }

  &.right {
    background-size: 1px 100%;
    background-position: left;
  }
}

GtkIconView,
iconview {
  @extend .view;
  background-color:transparent;

  &:backdrop{
    background-color:transparent;
  }
}

.rubberband,
rubberband {
  border: 1px solid darken($selected_bg_color, 10%);
  background-color: transparentize(darken($selected_bg_color, 10%), 0.8);
}


GtkFlow,
flowbox {
  rubberband { @extend rubberband; }

  flowboxchild {
    padding: 3px;
    border-radius: 3px;

    &:selected {
      @extend %selected_items;

      outline-offset: -2px;
    }
  }
}

GtkLabel,
label {
  &.separator {
    @extend .dim-label;

    color: $fg_color;

    &:backdrop { color: $backdrop_fg_color; }
  }

  .list-row:selected &,
  row:selected &,
  &:selected { @extend %nobg_selected_items; }

  selection {
    background-color: $selected_bg_color;
    color: $selected_fg_color;
  }

  &:disabled {
    color: $insensitive_fg_color;

    selection { @extend %selected_items:disabled; }

    &:backdrop { color: $backdrop_insensitive_color; }
  }

  &:backdrop {
    color: $backdrop_fg_color;

    selection { @extend %selected_items:backdrop; }
  }
}

.dim-label {
  opacity: 0.55;
  text-shadow: none;
}

%osd,
.osd {
  color: $osd_fg_color;
  border: none;
  background-color: $osd_bg_color;
  background-clip: padding-box;
  outline-color: transparentize($osd_fg_color, 0.7);
  text-shadow: 0 1px black;
  -gtk-icon-shadow: 0 1px black;

  &:backdrop {
    text-shadow: none;
    -gtk-icon-shadow: none;
  }
}

%selected_items {
  background-color: $selected_bg_color;

  @at-root %nobg_selected_items, & {
    color: $selected_fg_color;

    @if $variant == 'light' { outline-color: transparentize($selected_fg_color, 0.7); }

    &:disabled { color: mix($selected_fg_color, $selected_bg_color, 50%); }

    &:backdrop {
      color: $backdrop_selected_fg_color;

      &:disabled { color: mix($backdrop_selected_fg_color, $selected_bg_color, 30%); }
    }
  }
}

.monospace { font: Monospace; }