paper-gtk-theme/Paper/gtk-3.20/widgets/_level-bars.scss

/*************
 * Level Bar *
 *************/
levelbar {

  -GtkLevelBar-min-block-width: 32;
  -GtkLevelBar-min-block-height: 8;

  &:backdrop { transition: $backdrop_transition; }

  trough {
    @extend %scale_trough;
    margin: 0;
    padding:2px;
    border-radius:3px;
  }

  &.horizontal.indicator-discrete.fill-block { margin: 0 1px; }
  &.horizontal.discrete block { margin: 0 1px; }

  &.vertical.indicator-discrete.fill-block { margin: 1px 0; }
  &.vertical.discrete block { margin: 1px 0; }

  %fill-block,
  block {

    border-radius:2px;
    min-width: 32px;
    min-height: 2px;

    &.low,
    &.level-low {
      border:1px solid darken($warning_color,10%);
      background-color: $warning_color;

      &:backdrop { border:1px solid $warning_color; };
    }

    &.high,
    &.level-high {
      border:1px solid darken($selected_bg_color,10%);
      background-color: $selected_bg_color;

      &:backdrop { border:1px solid $selected_bg_color; }
    }

    &.full,
    &.level-full {
      border:1px solid darken($success_color,10%);
      background-color: $success_color;

      &:backdrop { border:1px solid $success_color; };
    }

    &.empty,
    &.level-empty {
      background-color: transparent;
      border:1px solid if($variant=='light', transparentize($fg_color,0.8),
                                          transparentize($fg_color,0.9));
      box-shadow: none;

      &:backdrop { border-color: transparentize($backdrop_fg_color,0.85); }
    }
  }

  // Trough
  &.horizontal,
  &.vertical {
    trough,
    .trough {
      @extend %scale_trough;
    }
  }


  // Vertical
  &.vertical {
    -GtkLevelBar-min-block-width: 8;
    -GtkLevelBar-min-block-height: 32;

    .fill-block,
    block {

      @extend %fill-block;

      min-width: 8px;
      min-height: 32px;
    }
  }
}