How do you add a css border to a single field on a table

I would like to show the full border selectively for an individual column/row on my table.

For records that the users need to submit to an approval process I am highlighting the row like so

CSS:
table.nx-skootable-data > tbody > tr.approvalissues-row > td {
    background-color:orange;
}

JS render snippet:
if(row.Needs_Approval__c) {
    field.item.element.addClass(“approvalissues-row”);
}

My next goal is to highlight the individual field that is causing the record to require approval by putting a border around it.

I’ve tried doing something similar to above:

using basically the same CSS format
table.nx-skootable-data > tbody > tr > td.approvalNeededBorder {
    border-width: 2px; 
    border-color: Black;
}

but this does not work…