.woocommerce-variations-table th, .woocommerce-variations-table tbody td {
    text-align: center !important;
}
table.woocommerce-variations-table td, table.dataTable.no-footer  {
    border: none !important;
}
table.woocommerce-variations-table th {
    border: none;
}
thead tr {
    border-bottom: 1px solid black;
}
table thead:first-child tr:first-child th {
    border-top: none !important;
}