设置对角线

效果图如下

html代码

<el-table :data="tableList" border stripe show-summary :summary-method="totalOutYear">
      <el-table-column prop="contractBelongToDeptName" label="指标" width="300" align="center"  fixed>
        <el-table-column
          prop="contractBelongToDeptName"
          label="填报部门"
          align="center"
          width="300"
          fixed
        ></el-table-column>
      </el-table-column>
      ...
</el-table>

style样式

/* 这里主要的作用就是用来强制修改element默认的样式*/
.el-table thead.is-group th {
  background: none;
  padding: 0px;
  height: 27.4px;
}

.el-table thead.is-group tr:first-of-type th:first-of-type {
  border-bottom: none; /*中间的横线去掉*/
}

.el-table thead.is-group tr:first-of-type th:first-of-type div.cell {
  text-align: right; /*上边文字靠右*/
}

.el-table thead.is-group tr:last-of-type th:first-of-type div.cell {
  text-align: left; /*下边文字靠左*/
}
/*核心代码*/
.el-table thead.is-group tr:first-of-type th:first-of-type:before {
  content: "";
  position: absolute;
  width: 1px;
  height: 300px; /*斜线的长度*/
  top: 0;
  left: 0;
  background-color: grey;
  opacity: 0.2;
  display: block;
  transform: rotate(-74.5deg); /*调整斜线的角度*/
  transform-origin: top;
}