elementui 表格行列合并出现混乱问题

效果图如下

```

/deep/ thead tr:nth-child(1) th:nth-child(1) {

  border-bottom: 0;

}

/deep/ thead tr:nth-child(2) th:nth-child(1) {

  border-right: 0;

}

.father {

  position: relative;

}

.wdlx {

  position: absolute;

  top: 7%;

  left: 11%;

  z-index: 999;

}

```