one-dark/cinnamon/sass/ui/panel.scss

//
// Panel
//
#panel {
  font-weight: bold;
  /* sets the height of horizontal panels */
  height: 40px;
  /* sets the width of vertical panels */
  width: 32px;
  /* Set the symbolic foreground color for icons, and importantly, the system tray applet icons */
  color: $fg_color;
  background-color: rgba(16, 16, 16, 0.1);

  &:highlight {
    border-image: none;
    background-color: transparentize($error_color, 0.5);
  }
}

.panel {
  &Left {
    spacing: 4px;

    &:dnd {
      background-gradient-direction: vertical;
      background-gradient-start: rgba(255, 0, 0, 0.05);
      background-gradient-end: rgba(255, 0, 0, 0.2);
    }
    &:ltr {
      padding-right: 4px;
    }
    &:rtl {
      padding-left: 4px;
    }

    &.vertical {
      padding: 0px;
      &:ltr {
        padding-right: 0px;
      }
      &:rtl {
        padding-left: 0px;
      }
    }
  }

  &Right {
    &:dnd {
      background-gradient-direction: vertical;
      background-gradient-start: rgba(0, 0, 255, 0.05);
      background-gradient-end: rgba(0, 0, 255, 0.2);
    }
    &:ltr {
      padding-left: 4px;
      spacing: 0px;
    }
    &:rtl {
      padding-right: 4px;
      spacing: 0px;
    }

    &.vertical {
      padding: 0px;
      &:ltr {
        padding-left: 0px;
        spacing: 0px;
      }
      &:rtl {
        padding-right: 0px;
        spacing: 0px;
      }
    }
  }

  &Center {
    spacing: 4px;

    &.vertical {
      padding-left: 0px;
      padding-right: 0px;
    }

    &:dnd {
      background-gradient-direction: vertical;
      background-gradient-start: rgba(0, 255, 0, 0.05);
      background-gradient-end: rgba(0, 255, 0, 0.2);
    }
  }

  &-top,
  &-bottom,
  &-left,
  &-right {
    color: $selected_fg_color;
    border: none;
    background-color: transparentize($panel_bg, 0.01);
    font-size: 1em;
    padding: 0px;
  }

  &-top {
    padding-right: 12px;
    box-shadow: 0 1px $borders_color;
  }

  &-bottom {
    padding-right: 12px;
    box-shadow: 0 -1px $borders_color;
  }

  &-left {
    box-shadow: 1px 0 $borders_color;
  }

  &-right {
    box-shadow: -1px 0 $borders_color;
  }

  &-dummy {
    background-color: transparentize($error_color, 0.5);

    &:entered {
      background-color: transparentize($error_color, 0.4);
    }
  }

  &-status-button {
    border-width: 0;
    -natural-hpadding: 3px;
    -minimum-hpadding: 3px;
    font-weight: bold;
    color: $panel_fg;

    &:hover {
    }
  }

  &-button {
    -natural-hpadding: 6px;
    -minimum-hpadding: 2px;
    font-weight: bold;
    color: green;
    transition-duration: 100;
  }
}

.system-status-icon {
  icon-size: 16px;
  padding: 0 1px;

  &.warning {
    color: $warning_color;
  }
  &.error {
    color: $error_color;
  }
}

//
// Panel Launchers Applet (panelLaunchers.js)
//
.panel-launchers {
  padding-left: 7px;
  spacing: 2px;

  & .launcher {
    padding-left: 2px;
    padding-right: 2px;
    padding-bottom: 2px;
    // border-bottom-width: 1px;
    transition-duration: 200;

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

  &.vertical {
    padding-top: 2px;
    padding-bottom: 2px;
    padding-left: 0px;
    padding-right: 0px;
    spacing: 1px;

    & .launcher {
      padding-top: 2px;
      padding-bottom: 2px;
    }
  }
}