tr.even/odd border-bottom is missing in IE

Good question! (BTW, the bottom border doesn't appear in IE6 either.)

However, the bottom border is missing from ALL themes, not just from Zen. So it looks like this is bug in Drupal core, not in Zen.

IE is ignoring the bottom border applied to the tr element in the modules/system/system.css file:

  tr.even, tr.odd {
    background-color: #eee;
    border-bottom: 1px solid #ccc;
    padding: 0.1em 0.6em;
  }

The border-bottom has to be applied to the td element in order for it to work under IE.

To keep the new rule at the same CSS specificity as tr.even, the attached patch uses: .even td .

D5's CSS is a known quantity. So we probably shouldn't change the way the CSS works for such a minor issue; it could potentially break someone’s theme. I've fixed this in Zen 5.x-1.x.

But let's get it fixed in D6.

Since margins could push table cells apart from each others, I would assume that having borders on table rows is not the same as having borders on table cells. So if you have some margin for your border cells, your patched version would display borders on the cell only (not where margins are in effect), but the previous code would display a border there as well. This is just an assumption, so let's think this through / experiment / test.

Cells can't have margins but there is cell spacing causing the gaps.

This is so subtle that I don't think it's worth fixing even for IE. Feel free to change the status back if you don't agree.