.#{$dropdown-prefix-cls} {
  $root: #{&};
  position: relative;
  display: inline-block;
  vertical-align: middle;
  cursor: pointer;
  //header
  &__header {
    display: block;
    padding: $dropdown-padding-y $dropdown-item-padding-x;
    margin-bottom: 0; // for use with heading elements
    font-size: $font-size-sm;
    color: $dropdown-header-color;
    white-space: nowrap; // as with > li > a
  }

  //backdrop
  &__backdrop {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: $zindex-dropdown-backdrop;
  }

  //toggle
  &__toggle {
    // Generate the caret automatically
    &::after {
      content: "\f292";
      @extend %aid-icon;
      transform: scale(1.4) translate(0, 0);
    }
    @include input-hover;
    &:disabled{
      border-color: transparent;
    }
  }

  i.aid-arrow-down-drop {
    transition: $transition-base;
  }

  //menu
  &__menu {
    position: absolute;
    top: auto;
    left: 0;
    z-index: $zindex-dropdown;
    float: left;
    padding: $dropdown-padding-y 0;
    margin: $dropdown-margin-top 0 0; // override default ul
    font-size: $font-size-sm; // Redeclare because nesting can cause inheritance issues
    color: $body-color;
    text-align: left; // Ensures proper alignment if parent has it changed (e.g., modal footer)
    list-style: none;
    background-color: $dropdown-bg;
    background-clip: padding-box;
    border: $dropdown-border-width solid $dropdown-border-color;
    // 用户自己按实际情况添加超过设定高度 加滚动条
    //max-height: $pre-scrollable-max-height;
    //overflow-y: auto;
    @include border-radius($border-radius);
    @include box-shadow($dropdown-box-shadow);

    // Menu positioning
    &--right {
      right: 0;
      left: auto; // Reset the default from `.dropdown-menu`
    }
    &--left {
      right: auto;
      left: 0;
    }
    &--top {
      top: auto;
      bottom: 100%;
      margin:0 0 $dropdown-margin-top 0;
    }
    ul {
      padding: 0;
      margin: 0;
      li {
        list-style: none;
      }
    }
  }

  #{$root}__menu{// 只有dropdown下的是默认隐藏
    top: 100%;
    display: none; // none by default, but block on "open" of the menu
    min-width:100%;
  }

  // Dividers
  &__divider {
    @include nav-divider($dropdown-divider-bg);
    margin: 0;
  }

  // item
  &__item{
    display: block;
    width: 100%; // For `<button>`s
    min-width: $dropdown-item-min-width;
    height: 32px;
    line-height: 32px;
    padding: $dropdown-item-padding-y $dropdown-item-padding-x;
    clear: both;
    font-weight: $font-weight-normal;
    color: $dropdown-link-color;
    text-align: inherit; // For `<button>`s
    white-space: nowrap; // prevent links from randomly breaking onto new lines
    background: none; // For `<button>`s
    border: 0; // For `<button>`s
    cursor: pointer;

    @include hover-focus {
      color: $dropdown-link-hover-color;
      text-decoration: none;
      background-color: $dropdown-link-hover-bg;
    }

    //focus
    //响应‘↑’ ‘↓’ 键
    &--focus {
      color: $dropdown-link-hover-color;
      text-decoration: none;
      background-color: $dropdown-link-hover-bg;
    }

    //disabled
    @include status-disabled {
      color: $dropdown-link-disabled-color !important;
      background-color: transparent;
      @if $enable-gradients {
        background-image: none;
      }
      @include hover-focus {
        color: $dropdown-link-disabled-color !important;
        background-color: transparent;
      }
    }

    //checked
    @include checked-active {
      color: $dropdown-link-hover-color;
      text-decoration: none;
      background-color:$dropdown-link-active-bg;
    }
    i{
      vertical-align: middle;
    }

    // 二级菜单
    .popover-wrap{
      width:calc(100% + #{$dropdown-item-padding-x}*2);
      margin-left:-$dropdown-item-padding-x;
      padding-left:$dropdown-item-padding-x;
    }
    #{$root}__menu{
      margin-top: -$dropdown-item-padding-y;
    }

    .aid-chevron-right {
      margin-right: $dropdown-item-padding-x;
      float: right;
    }
  }


  //dropdown-group
  &-group {
    list-style: none;
    padding-left: 0;
    ul {
      list-style: none;
      padding-left: 0;
      margin:0;
    }
    span {
      display: block;
      width: 100%; // For `<button>`s
      padding: $dropdown-group-title-padding-y $dropdown-item-padding-x;
      clear: both;
      font-weight: $font-weight-normal;
      color: $dropdown-group-title-color;
      font-size: $dropdown-group-title-font-size;
      white-space: nowrap; // prevent links from randomly breaking onto new lines
    }
    .#{$dropdown-prefix-cls}__item {
      padding-left: $dropdown-item-padding-x*2;
      padding-right: $dropdown-item-padding-x*2;
    }
  }

  //dropdown--open
  &--open{
    >#{$root}__menu{
      display: block;
    }
    // Remove the outline when :focus is triggered
    > a {
      outline: 0;
    }
    i.aid-chevron-down {
      transition: all $transition-time;
      transform: rotate(180deg);
    }
  }
}