d. FF and NG differ by a px (rounding?).
</p>
<table style="width:calc(100px + 68px)" data-expected-width=168>
  <tr>
    <td style="width:50%" data-expected-width=63>50%</td>
    <td style="width:30%" data-expected-width=42>30%</td>
    <td style="width:20%" data-expected-width=31>20%</td>
  </tr>
</table>

<p 18 class="testdesc">Assignable: 100px;columns add to 50%, auto width
Columns grow proportional to percent.
Slight rounding differences between NG and FF.
<table style="width:calc(100px + 68px)" data-