We have this:

EXAMPLE 53 (http://dev.w3.org/csswg/selectors4/#column-combinator)
The following example makes cells C, E, and G yellow.

col.selected || td {
  background: gray;
  color: white;
  font-weight: bold;
}

<table>
  <col span="2">
  <col class="selected">
  <tr><td>A <td>B <td>C
  <tr><td colspan="2">D <td>E
  <tr><td>F <td colspan="2">G
</table>

First, we don't have any yellow style, and second, I think this selector should not match G cell (only C and E).