How do I make one table column fill all the spare horizontal space?

you can use max-width:99%; on the first column and give fixed sizes on the other columns (I used pixels sized columns).

<table style="width: 100%;">
  <tr>
    <td style="max-width: 99%">
      Will max
    </td>
    <td style='width:110px;'> 
      fixed size here
    </td>
  </tr>
</table>

You can apply width="99%" on that column. For example:

<table> 
  <tr> 
    <td width="99%">Name</td> 
    <td>Qty</td> 
    <td>Actions</td> 
  </tr> 
</table>