message: TabbarItem: supported Component, fixed tap animations
diff: .TabbarItem {
  - flex-shrink: 0;
  - max-width: 100%;
  - flex-grow: 1;
  - flex-basis: 0;
  - overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  outline: none;
  padding: 0;
  - margin: 0;
  background: transparent;
  + height: var(--tabbar_height);
  + position: relative;
  +}
  +
  +.Tabbar .TabbarItem {
  + flex-shrink: 0;
  + max-width: 100%;
  + min-width: 0;
  + flex-grow: 1;
  + flex-basis: 0;
  }
  .TabbarItem--selected {
  color: var(--tabbar_active_icon);
  }
  +.TabbarItem__tappable {
  + position: absolute;
  +}
  +
  .TabbarItem__in {
  align-self: center;
  display: flex;
  - max-width: 100%;
  padding: 0 2px;
  - box-sizing: border-box;
  align-items: center;
  justify-content: center;
  + pointer-events: none;
  + height: 100%;
  + overflow: hidden;
  +}
  +
  +.Tabbar--l-vertical .TabbarItem--text .TabbarItem__in {
  + position: relative;
  + top: 2px;
  }
  .Tabbar--l-vertical .TabbarItem__in {
  * Android
  */
  -.TabbarItem--android::after {
  - content: '';
  - padding-bottom: 100%;
  - width: 100%;
  -}
  -
  -.TabbarItem--android {
  - transform: translateY(calc(-1 * (100% - var(--tabbar_height)) / 2));
  +.TabbarItem--android .TabbarItem__tappable {
  + position: absolute;
  + width: calc(100% + 16px);
  + padding-bottom: calc(100% + 16px);
  border-radius: 50%;
  }
  border-bottom-right-radius: 0;
  }
  -.TabbarItem--android .TabbarItem__in {
  - position: absolute;
  - left: 0;
  - top: 0;
  - width: 100%;
  - height: 100%;
  -}
  -
  -.Tabbar--android.Tabbar--l-vertical .TabbarItem--text .TabbarItem__in {
  - top: 2px;
  -}
  -
  /**
  * iOS
  */
  -.TabbarItem--ios {
  - transition: transform .07s var(--ios-easing);
  +.TabbarItem--ios .TabbarItem__tappable {
  + width: 100%;
  + height: 100%;
  + top: 0;
  + left: 0;
  }
  -.TabbarItem--ios.TabbarItem--active {
  - transform: scale(.96);
  +.TabbarItem--ios .TabbarItem__in {
  + transition: transform .07s var(--ios-easing);
  }
  -.Tabbar--ios.Tabbar--l-vertical .TabbarItem--text .TabbarItem__in {
  - position: relative;
  - top: 2px;
  +.TabbarItem--ios .TabbarItem__tappable--active + .TabbarItem__in {
  + transform: scale(.96);
  }
  