test.html

<style type="text/css">

    .ascii-table {
        font: medium/1 monospace;
        margin: 1em;
        display: inline-block;
        position: relative;
    }
    .ascii-table table {
        border-collapse: collapse;
    }
    .ascii-table td {
        border: 1px dashed #000;
        padding: .5em;
        position: relative;
    }
    .ascii-table tr td:before {
        position: absolute;
        width: 15px;
        height: 15px;
        content: "";
        top: -8px;
        left: -8px;
    }
    .ascii-table tr td:last-child:after, .ascii-table tr:last-child td:after {
        position: absolute;
        width: 15px;
        height: 15px;
        content: "";
        bottom: -8px;
        right: -8px;
    }
    .ascii-table:before {
        position: absolute;
        width: 15px;
        height: 15px;
        content: "";
        top: -7px;
        right: -7px;
    }
    .ascii-table:after {
        position: absolute;
        width: 15px;
        height: 15px;
        content: "";
        bottom: -7px;
        left: -7px;
    }
</style>

    <div class="ascii-table">
        <table>
            <tr>
                <td>Jill</td><td>Smith</td><td>50</td>
            </tr>
        </table>
    </div>
    <div class="ascii-table">
        <table>
            <tr>
                <td>Jill</td><td>Smith</td><td>50</td>
            </tr>
            <tr>
                <td>Eve</td><td>Jackson</td><td>94</td>
            </tr>
        </table>
    </div>
    <div class="ascii-table">
        <table>
            <tr>
                <td>Jill</td><td>Smith</td><td>50</td>
            </tr>
            <tr>
                <td>Eve</td><td>Jackson</td><td>94</td>
            </tr>
            <tr>
                <td>John</td><td>Doe</td><td>75</td>
            </tr>
        </table>
    </div>