Outer border disappears when hiding outer columns in an s-table__bx table
Describe the bug
Hiding the first or the last column in a table with only horizontal borders (.s-table__bx) via sm:d-none results in the outer border of the table going AWOL on the corresponding side.
To Reproduce Markup:
<table class="s-table s-table__bx">
<thead>
<tr>
<th scope="col" class="sm:d-none">Something</th>
<th scope="col">Another</th>
<th scope="col">Thing</th>
<th scope="col">Testing</th>
</tr>
</thead>
<tbody>
<tr>
<td class="sm:d-none">Hello</td>
<td>Goodbye</td>
<td>Maybe</td>
<td>Wat</td>
</tr>
</tbody>
</table>
Toss that into a CodePen or similar, and then resize the window down.
Expected behavior The outer table border should not disappear.
Screenshots
Before resizing:

After resizing:

Desktop (please complete the following information):
- OS: Windows 10
- Browser: Chrome
- Version 75.0.3770.142
Additional context
The workaround is to add the sm:bl bc-black-3 brw0 classes to the second column of the table (blw0 for the penultimate column).
This issue also applies to rows as well. I'm not sure how we can avoid this, since :first-child is working as designed. 🤔
Related, there's a similar problem if the first or last item in a s-btn-group is hidden. (No corner radii.)