Colloid-gtk-theme/src/sass/libadwaita/widgets/_dialogs.scss

.dialog-action-area {
  margin: $base_padding;
  border-spacing: $base_padding;
}

/****************
 * Print dialog *
*****************/

window.print {
  drawing {
    color: $window_fg_color;
    background: none;
    border: none;
    padding: 0;

    paper {
      background-color: white;
      color: transparentize(black, .2);
      background-clip: padding-box;
      border: 1px solid $border_color;
    }
  }

  headerbar.titlebar {
    @extend .flat;
  }

  .dialog-action-box {
    @extend .view;
  }
}

/********************
 * Page setup dalog *
 ********************/

window.pagesetup {
  headerbar.titlebar {
    @extend .flat;
  }
}

/******************
 * GtkAboutDialog *
 ******************/

window.aboutdialog {
  headerbar.titlebar {
    @extend .flat;
  }

  image.large-icons {
    -gtk-icon-size: 128px;
  }
}

/*************************
 * GtkColorChooserDialog *
 *************************/
window.colorchooser {
  headerbar.titlebar {
    @extend .flat;
  }
}

/*************
 * AdwDialog *
 *************/

floating-sheet {
  > dimming {
    background-color: gtkalpha($shade_color, 2);
  }

  > sheet {
    border-radius: $window_radius;
    box-shadow: 0 2px 8px 2px transparentize(black, 0.93),
                0 3px 20px 10px transparentize(black, 0.95),
                0 6px 32px 16px transparentize(black, 0.98),
                0 0 0 1px $shade_color;
    outline: 1px solid $window_outline_color;
    outline-offset: -1px;
  }
}

dialog.bottom-sheet {
  &.landscape sheet {
    margin-left: 30px;
    margin-right: 30px;

    > outline {
      &.flush-left, &.flush-right, &.flush-left.flush-right {
        box-shadow: inset 1px 0 $window_outline_color,
                    inset -1px 0 $window_outline_color,
                    inset 0 1px $window_outline_color;
      }
    }
  }
}

dialog-host > dialog.background {
  background: none;

  sheet {
    background-color: $window_bg_color;
    color: $window_fg_color;
  }
}

dialog-host > dialog.view {
  background: none;

  sheet {
    @extend %view;
  }
}

dialog-host > dialog.osd {
  background: none;

  sheet {
    @extend %osd;
  }
}