dots/usr/share/themes/Dracula/gtk-3.20/widgets/_progress-bars.scss

/*****************
 * Progress bars *
 *****************/
progressbar {
  // sizing
  &.horizontal {
    trough,
    progress { min-height: 6px; }
  }

  &.vertical {
    trough,
    progress { min-width: 6px; }
  }

  &.horizontal progress { margin: 0; } // the progress node is positioned after the trough border
  &.vertical progress { margin: 0; }   // this moves it over it.


  // FIXME: insensitive state missing and some other state should be set probably
  font-size: smaller;
  color: transparentize($fg_color, 0.6);

  &:backdrop {
    box-shadow: none;
    transition: $backdrop_transition;
  }

  trough { @extend %scale_trough; }

  &:backdrop trough { @extend %scale_trough:backdrop; } // looks like states are not passed to the trough component here

  progress {
    @extend %scale_highlight;
  }

  &:backdrop progress { @extend %scale_highlight:backdrop; } // states not passed here as well

  &.osd { // progressbar.osd used for epiphany page loading progress
    min-width: 3px;
    min-height: 3px;
    background-color: transparent;

    trough {
      border-style: none;
      border-radius: 0;
      background-color: transparent;
      box-shadow: none;
    }

    progress {
      border-style: none;
      border-radius: 0;
    }
  }
}