message: feat(NavBar): improve active feedback
diff: &__arrow {
  min-width: 1em;
  + margin-right: @padding-base;
  font-size: @nav-bar-arrow-size;
  -
  - + .van-nav-bar__text {
  - margin-left: -20px;
  - padding-left: 25px;
  - }
  }
  &--fixed {
  bottom: 0;
  display: flex;
  align-items: center;
  + padding: 0 @padding-md;
  font-size: @font-size-md;
  cursor: pointer;
  +
  + &:active {
  + opacity: @active-opacity;
  + }
  }
  &__left {
  - left: @padding-md;
  + left: 0;
  }
  &__right {
  - right: @padding-md;
  + right: 0;
  }
  &__text {
  - margin: 0 -@padding-md;
  - padding: 0 @padding-md;
  color: @nav-bar-text-color;
  -
  - &:active {
  - background-color: @active-color;
  - }
  }
  }
  