#ctree-tree-drop-styles () {
  // prefix
  @tree-drop-prefix: ~"@{ctree-prefix}-tree-drop";
  @tree-search-prefix: ~"@{ctree-prefix}-tree-search";
  @tree-dropdown-prefix: ~"@{ctree-prefix}-dropdown";

  // TreeDrop
  .@{tree-drop-prefix} {
    // 容器
    &__wrapper {
      position: relative;
    }

    // 下拉框触发区域
    &__reference {
      cursor: pointer;
    }

    // 触发区域
    &__display {
      // 输入框
      &-input {
        position: relative;
        user-select: none;
        padding-right: 20px;

        &-text {
          display: block;
          height: 100%;
          line-height: 22px;
        }

        &-placeholder {
          color: @ctree-color-input-placeholder;
        }

        &_focus {
          border-color: @ctree-color-input-border;
          box-shadow: 0 0 0 2px fade(@ctree-color-primary, 20%);
        }
      }

      // 图标
      &-icon {
        @icon-size: 14px;
        .icon () {
          position: absolute;
          top: 8px;
          right: 3px;
          width: @icon-size;
          height: @icon-size;
          box-sizing: border-box;
        }

        // 下拉图标
        &-drop {
          @scale: 0.5;
          @translate: -(@icon-size / 2) * @scale;
          @transform-rest: scale(@scale) translateX(@translate) translateY(@translate);

          .icon();
          border: 3px solid @ctree-color-sub;
          border-top: none;
          border-left: none;
          transform: rotate(45deg) @transform-rest;
          transition: transform .2s ease-in-out;

          &_active {
            transform: rotate(225deg) @transform-rest;
          }
        }

        // 清除图标
        &-clear {
          @scale: 0.9;
          .pseudo () {
            @thick: 1px;
            @offset: (@icon-size - @thick) / 2;
            @diff: 7px;

            content: "";
            width: @thick;
            height: @icon-size - @diff;
            display: block;
            background-color: #fff;
            position: absolute;
            top: @diff / 2;
            left: @offset;
          }

          .icon();
          border-radius: 50%;
          background-color: @ctree-color-sub;
          overflow: hidden;
          transform: scale(@scale) rotate(45deg);
          display: none;

          &::before {
            .pseudo();
          }

          &::after {
            .pseudo();
            transform: rotate(90deg);
          }
        }
      }

      &-input:hover &-icon-clear {
        display: block;
      }
    }

    // 下拉框
    &__dropdown {
      position: absolute;
      top: -999px;
      left: -999px;
      box-shadow: 0 1px 6px fade(#000, 20%);
      border-radius: 4px;
      margin: 5px 0;
      padding: 5px 0;
      transform-origin: center top 0px;
      background-color: #fff;
      z-index: 9999;

      .@{tree-search-prefix} {
        // TreeSearch 搜索区域
        &__search {
          border-bottom: 1px solid @ctree-color-border;
          padding-bottom: 5px;
          height: 38px;
        }

        // TreeSearch 树区域
        &__tree-wrapper {
          padding-top: 5px;
        }
      }
    }
  }

  // Dropdown animation
  .@{tree-dropdown-prefix} {
    &-enter, &-leave-to {
      opacity: 0;
      transform: scaleY(0.8)
    }

    &-enter-active, &-leave-active {
      transition: opacity .3s,
                  transform .3s;
    }
  }
}

#ctree-tree-drop-styles();