ant-design/style/components/tree.less

@treePrefixCls: ant-tree;

.@{treePrefixCls} {
  margin:0; padding:5px;
  li {
    padding: 0;  margin: 0;
    list-style: none;  white-space: nowrap;  outline: 0;
    ul {
       margin:0; padding:0 0 0 18px;
       &.@{treePrefixCls}-line{
         background:url(https://t.alipayobjects.com/images/T13BtfXl0mXXXXXXXX.gif) 0 0 repeat-y;
       }
    }
    a {
      display: inline-block;
      padding:1px 3px 0 0; margin:0;
      cursor:pointer; height:20px;
      text-decoration:none; vertical-align:top;
    }
    span {
      line-height:20px;  margin-right:2px;
      &.@{treePrefixCls}-button {
        line-height:0; margin:0; width:16px; height:16px;
        display: inline-block; vertical-align:middle;
        border:0 none; cursor: pointer;outline:none;
        background-color:transparent; background-repeat:no-repeat; background-attachment: scroll;
        background-image:url("https://t.alipayobjects.com/images/T1NcthXkFdXXXXXXXX.png");
        &.@{treePrefixCls}-switcher {
          &-disabled {
            background: #fff; position: relative;
            &:after{content: '-'; position: absolute; top: 8px; left: 6px; color: gray;}
          }
          &.@{treePrefixCls}-roots_open { background-position: -94px 0}
          &.@{treePrefixCls}-roots_close{ background-position:-76px 0}
          &.@{treePrefixCls}-center_open{ background-position:-94px -18px}
          &.@{treePrefixCls}-center_close{ background-position:-76px -18px}
          &.@{treePrefixCls}-bottom_open{ background-position:-94px -36px}
          &.@{treePrefixCls}-bottom_close{ background-position:-76px -36px}
          &.@{treePrefixCls}-noline_open{ background-position:-94px -72px}
          &.@{treePrefixCls}-noline_close{ background-position:-76px -72px}
        }
        &.@{treePrefixCls}-chk {
          width: 15px;  height: 15px; margin: 0 3px;
          &-disabled {
            background-position: 0 -28px;
          }
          &.@{treePrefixCls}-checkbox_false_full {background-position:0 0}
          &.@{treePrefixCls}-checkbox_false_full_focus {background-position:0 -14px}
          &.@{treePrefixCls}-checkbox_false_part {background-position:0 -28px}
          &.@{treePrefixCls}-checkbox_false_part_focus {background-position:0 -42px}
          &.@{treePrefixCls}-checkbox_false_disable {background-position:0 -56px}
          &.@{treePrefixCls}-checkbox_true_full {background-position:-14px 0}
          &.@{treePrefixCls}-checkbox_true_full_focus {background-position:-14px -14px}
          &.@{treePrefixCls}-checkbox_true_part {background-position:-14px -30px}
          &.@{treePrefixCls}-checkbox_true_part_focus {background-position:-14px -42px}
          &.@{treePrefixCls}-checkbox_true_disable {background-position:-14px -56px}
        }
      }
    }
  }
  &-treenode-disabled {
    >span, >a {
      color: gray;
    }
  }
  &-selected{
    background-color:#FFE6B0;
    border:1px #FFB951 solid; opacity:0.8;
  }
  &-icon__open {
    margin-right: 2px;
    background-position: -110px -16px;
    vertical-align: top;
  }
  &-icon__close {
    margin-right: 2px;
    background-position: -110px 0;
    vertical-align: top;
  }
}