ionic-framework/ionic/components/tabs/tabs.scss

// Tabs
// --------------------------------------------------

$tabbar-background-color:        $toolbar-background-color !default;

$tab-button-text-color:           $toolbar-text-color !default;
$tab-button-active-color:         $toolbar-active-color !default;
$tab-button-inactive-color:       $toolbar-inactive-color !default;
$tab-button-padding:              10px !default;
$tab-button-min-width:            80px !default;
$tab-button-max-width:            240px !default;


ion-tabs {
  display: flex;
  flex-direction: column;

  overflow: hidden;
  width: 100%;
  height: 100%;
  max-width: 100%;
  max-height: 100%;
  margin: 0;
  padding: 0;
}

ion-tab {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  flex-direction: column;

  display: none;
  &.show-tab {
    display: flex;
  }
}

ion-tabs > ion-navbar-section {
  order: $flex-order-tabbar-navbar;
}

ion-tabbar-section {
  position: relative;
  order: $flex-order-tabbar-bottom;
}

[tabbar-placement=top] ion-tabbar-section {
  order: $flex-order-tabbar-top;
}

tabbar {
  position: relative;
  display: flex;
  justify-content: center;
  overflow: hidden;
  background: $tabbar-background-color;
}

.tab-button {
  position: relative;
  z-index: 0;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: center;
  flex: 1;
  align-self: center;
  align-items: center;

  margin: 0;
  padding: $tab-button-padding;
  min-width: $tab-button-min-width;
  max-width: $tab-button-max-width;

  text-align: center;
  cursor: pointer;
  @include user-select-none();

  color: $tab-button-inactive-color;
  border: 0;
  border-radius: 0;
  background: none;
}

.tab-button:hover:not(.disable-hover),
.tab-button[aria-selected=true] {
  color: $tab-button-active-color;
}

.tab-button-text {
  margin-top: 3px;
  margin-bottom: 2px;
}

.tab-button-text,
.tab-button-icon {
  align-self: center;

  min-width: 26px;
  max-width: 100%;

  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;

  display: none;
}

.has-icon .tab-button-icon,
.has-title .tab-button-text {
  display: block;
}

.has-title-only .tab-button-text {
  white-space: normal;
}

tab-highlight {
  display: none;
}

[tabbar-icons=bottom] .tab-button {
  .tab-button-icon {
    order: 10;
  }
}

[tabbar-icons=left] .tab-button {
  flex-direction: row;

  .tab-button-icon {
    text-align: right;
    padding-right: 8px;
  }
}

[tabbar-icons=right] .tab-button {
  flex-direction: row;

  .tab-button-icon {
    order: 10;
    text-align: left;
    padding-left: 8px;
  }
}

[tabbar-icons=hide] .tab-button-icon {
  display: none;
}


// Tabbar Color Generation
// --------------------------------------------------

@each $color-name, $color-value in $colors {

  tabbar[#{$color-name}] {
    background-color: $color-value;

    .tab-button {
      color: inverse($color-value);
    }

    .tab-button:hover:not(.disable-hover),
    .tab-button[aria-selected=true] {
      color: inverse($color-value);
    }
  }

}