title: blueprint issue
body: <p>I have the following layout. the first row prints just fine, but the beginning of the 2nd row starts where the 2nd div on the 2nd row should be. If I set the span of the last div in the 1st row to 3, the 2nd prints fine.</p>
  
  <p>the parent div is 670 pixels and each child is 160 (including 10px right margin) All 4 should fit in a row, but they are not, whats wrong here?</p>
  
  <p>I bassically want a parent div of 17 spans with rows of 4 child divs each with  span of 4.</p>
  
  <pre><code>&lt;div id="parent" class="span-17 last&gt;
     &lt;div id="child" class="span-4"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
    &lt;div id="child" class="span-4"&gt;
    &lt;span&gt;content&lt;/content&gt;
    &lt;span&gt; image &lt;/content&gt;
  &lt;/div&gt;
    &lt;div id="child" class="span-4"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
    &lt;div id="child" class="span-4 last"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
  &lt;!--row 2 starts --&gt;
    &lt;div id="child" class="span-4"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
    &lt;div id="child" class="span-4"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
    &lt;div id="child" class="span-4"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
    &lt;div id="child" class="span-4 last"&gt;
     &lt;span&gt;content&lt;/content&gt;
     &lt;span&gt; image &lt;/content&gt;
     &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>