app/node_modules/ng-zorro-antd/table/style/radius.less

// ================================================================
// =                         Border Radius                         =
// ================================================================
.@{table-prefix-cls} {
  /* title + table */
  &-title {
    border-radius: @table-border-radius-base @table-border-radius-base 0 0;
  }

  &-title + &-container {
    border-top-left-radius: 0;
    border-top-right-radius: 0;

    table {
      border-radius: 0;

      > thead > tr:first-child {
        th:first-child {
          border-radius: 0;
        }

        th:last-child {
          border-radius: 0;
        }
      }
    }
  }

  /* table */
  &-container {
    border-top-left-radius: @table-border-radius-base;
    border-top-right-radius: @table-border-radius-base;

    table > thead > tr:first-child {
      th:first-child {
        border-top-left-radius: @table-border-radius-base;
      }

      th:last-child {
        border-top-right-radius: @table-border-radius-base;
      }
    }
  }

  /* table + footer */
  &-footer {
    border-radius: 0 0 @table-border-radius-base @table-border-radius-base;
  }
}