Question

I have a variable number of table rows (n), and I would like the border bottom to apply to rows 0..(n-1)

how do I do that?

Answer 1

You have two options: (1) adding a specialized class in the HTML to the last row; or (2) using the :last-child pseudo class in your CSS.

Option 1: Specialized Class

If you can apply classes to your HTML, you can add a specialized class to the final row. If your markup is being generated by a server-side script (eg. a PHP script), you will need to edit that script to add similar markup.

HTML:

<table>
   <tr>
      <td>
      </td>
   </tr>
   <tr>
      <td>
      </td>
   </tr>
   <tr class="last">
      <td>
      </td>
   </tr>
</table>

CSS:

table
{
   border-collapse:collapse;
}
tr
{
   border-bottom: 1px solid #000;
}
tr.last
{
   border-bottom: none;
}

Option 2: CSS Pseudo Class

The alternative is to use the :last-child CSS pseudo class. Using the :last-child class doesn’t require any changes to the HTML and so may be a better choice if you aren’t able to change the HTML. The CSS is almost identical to the above:

CSS:

table
{
   border-collapse:collapse;
}
tr
{
   border-bottom: 1px solid #000;
}
tr:last-child
{
   border-bottom: none;
}

The drawback of this approach is that versions of Internet Explorer before 9 don’t support the :last-child pseudo class.