title: Borders not shown in Firefox with border-collapse on table, position: relative on tbody, or background-color on cell
body: <p>Consider the following HTML:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;html&gt;
  &lt;head&gt;
      &lt;style&gt;
          TABLE.data TD.priceCell
          {
              background-color: #EEE;
              text-align: center;
              color: #000;
          }
      
          div.datagrid table
          {
              border-collapse: collapse;
          }
      
          div.datagrid table tbody
          {
              position: relative;
          }
      &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div id="contents" class="datagrid"&gt;
          &lt;table class="data" id="tableHeader"&gt;
              &lt;thead&gt;
                  &lt;tr class="fixed-row"&gt;
                      &lt;th&gt;Product&lt;/th&gt;
                      &lt;th class="HeaderBlueWeekDay"&gt;Price&lt;/th&gt;
                      &lt;th class="HeaderBlueWeekDay"&gt;Discount&lt;/th&gt;
                  &lt;/tr&gt;
              &lt;/thead&gt;
              &lt;tbody&gt;
                  &lt;tr style="font-style: italic;"&gt;
                      &lt;td&gt;Keyboard&lt;/td&gt;
                      &lt;td class="priceCell"&gt;20&lt;/td&gt;
                      &lt;td style="border-right: #3D84FF 1px solid; border-left: #3D84FF 1px solid;" class="priceCell"&gt;2&lt;/td&gt;
                  &lt;/tr&gt;
              &lt;/tbody&gt;
          &lt;/table&gt;
      &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Notice that the last cell has a left and a right border in its inline style. You (or at least I) would expect this to be visible. In IE, this is the case. But in Firefox (6), this is not. You can solve this by:</p>
  
  <ul>
  <li>Removing position relative on <code>div.datagrid table tbody</code> in the CSS </li>
  <li>Changing <code>div.datagrid table tbody</code> to <code>div.datagrid table</code> in the CSS </li>
  <li>Removing the <code>background-color</code> on <code>table.data td.priceCell</code> in the CSS </li>
  <li>Removing the <code>border-collapse</code> on <code>div.datagrid table</code> in the CSS </li>
  </ul>
  
  <p>This is a simplified version of our code; we also solved it (by choosing option 2). But what I'm wondering about is:</p>
  
  <ul>
  <li>Is this a bug in Firefox?</li>
  <li>Is this a bug in IE?</li>
  </ul>
  
  <p>And especially: what is the reason Firefox wouldn't show the borders when the CSS is as it is?</p>