tr.t_sub_replies td:nth-child(2) {
    border-bottom: 1px solid #b3aeae;
    margin-left: 7%;
    margin-bottom: 0;
    padding-bottom: 0 !important;
}

p {
    margin: 0;
    line-height: 20px;
}

<td width="20%" align="center"><p><b>Harish</b> <span style="font-size:12px;">Harish</span></p><p> <span style="font-size:11px;">Customer</span></p><p>06/18/2020 09:13 am</p></td>