How to make <div> fill <td> height

If you give your TD a height of 1px, then the child div would have a heighted parent to calculate it's % from. Because your contents would be larger then 1px, the td would automatically grow, as would the div. Kinda a garbage hack, but I bet it would work.

CSS height: 100% only works if the element's parent has an explicitly defined height. For example, this would work as expected:

td {
    height: 200px;
}

td div {
    /* div will now take up full 200px of parent's height */
    height: 100%;
}

Since it seems like your <td> is going to be variable height, what if you added the bottom right icon with an absolutely positioned image like so:

.thatSetsABackgroundWithAnIcon {
    /* Makes the <div> a coordinate map for the icon */
    position: relative;

    /* Takes the full height of its parent <td>.  For this to work, the <td>
       must have an explicit height set. */
    height: 100%;
}

.thatSetsABackgroundWithAnIcon .theIcon {        
    position: absolute;
    bottom: 0;
    right: 0;
}

With the table cell markup like so:

<td class="thatSetsABackground">  
  <div class="thatSetsABackgroundWithAnIcon">    
    <dl>
      <dt>yada
      </dt>
      <dd>yada
      </dd>
    </dl>
    <img class="theIcon" src="foo-icon.png" alt="foo!"/>
  </div>
</td>

Edit: using jQuery to set div's height

If you keep the <div> as a child of the <td>, this snippet of jQuery will properly set its height:

// Loop through all the div.thatSetsABackgroundWithAnIcon on your page
$('div.thatSetsABackgroundWithAnIcon').each(function(){
    var $div = $(this);

    // Set the div's height to its parent td's height
    $div.height($div.closest('td').height());
});