title: grid-column-end has to be one number bigger, than there are columns
body: <p>Given this CSS grid example:</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-css lang-css prettyprint-override"><code>ul {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    padding: 0;
    list-style: none;
  }
  
  li {
    background: rgba(128, 0, 0, .5);
    border: 1px solid #666;
  }
  
  .four {
    grid-area: 2/1/2/4;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;ul&gt;
    &lt;li&gt;Col 1&lt;/li&gt;
    &lt;li&gt;Col 2&lt;/li&gt;
    &lt;li&gt;Col 3&lt;/li&gt;
    &lt;li class="four"&gt;Col 4&lt;/li&gt;
  &lt;/ul&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>Can anyone explain, why I do I need to set the <code>grid-column-end</code> to <code>4</code> if there are only three columns?</p>
  <p>From what I understand from the MDN docs, the grid-area should be <code>grid-area: 2/1/2/3;</code> – but that would result in the <code>li.four</code> only spanning two columns.</p>
  <p>To me this seems like a strange bug, because I need to span column 1-4 to actually have a visual span of a row over three columns.</p>