views/style/sass/lib/data_table.scss

table.dataTable thead{
  th div.DataTables_sort_wrapper{
    font-weight: normal !important;
  }
  tr {
    background-color: $thead-background;

    th.ui-state-default {
      background: transparent !important;
      color: #fff !important;
    }
  }
}

table.dataTable tr.odd,
table.dataTable tr.odd td.sorting_1{
  background-color: $gray-lighter !important;
}
table.dataTable tr.even td.sorting_1{
  background-color: #fff;
}
table.dataTable thead th div.DataTables_sort_wrapper {
  font-weight: bold;
}