调整elment-ui的表头字体大小

<el-table :header-cell-style="{fontSize:'24px'}"
                  :data="screeningHistoryGroups"
                  :height="670"
                  @row-click="rowClick"
                >
                  <el-table-column
                    prop="utilName"
                    label="筛查工具"
                    show-overflow-tooltip
                  />
</el-table>