<table class="table-grid">
    <tr>
        <td>
            First cell in main table. 
        </td>
        <td>
            <table class="table-grid">
                <tr>
                    <td>
                        First cell in, first nested table. 
                    </td>
                    <td>
                        <table class="table-grid">
                            <tr>
                                <td>
                                  Second nested table,  nested table, cell
                                </td>
                            </tr>
                            <tr>
                                <td>
                                    Second nested table,  nested table, cell
                                </td>
                            </tr>
                        </table>
                    </td>
                </tr>
            </table>
        </td>
    </tr>
</table>

.table-grid{

  border-collapse: collapse;
}
.table-grid > tr > td {
  padding: 0;
}

.table-grid>thead>tr>th,
.table-grid>tbody>tr>th,
.table-grid>tfoot>tr>th,
.table-grid>thead>tr>td,
.table-grid>tbody>tr>td,
.table-grid>tfoot>tr>td {
  border: 1px solid red;
}

.table-grid .table-grid td
{
  border-top:0;
  border-right: 1px solid red;
  border-bottom: 0;
  border-left: 0;
}

.table-grid .table-grid td:last-child,
.table-grid .table-grid th:last-child {
  border-right: 0;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.