/deep/.el-table .sort-caret.descending{
  border-top-color:black;
}
/deep/.el-table .sort-caret.ascending{
  border-bottom-color:black;
}

/deep/ .descending .sort-caret.descending{
  border-top-color:#3958FE;
}
/deep/ .ascending  .sort-caret.ascending{
  border-bottom-color:#3958FE;
}

默认是灰色 现在改成默认为black 且点击上三角和下三角颜色变成:#3958FE