title: polymer: Grid Layout
body: <p>I am trying create a sort of Grid Layout in an web app through polymer's layouts. 
  I am using div elements with the 'wrap' attributes but (as expected) they end irregularly. I'd like them to end at the same width and create a regular shape. </p>
  
  <p>here is a snippet of what I am doing (part of a Jinja2 template)</p>
  
  <pre><code>&lt;div horizontal layout wrap style&gt;
          {% for el in elements %}    
          &lt;my-card&gt; {{el.content}} &lt;/maker-card&gt;
          {% endfor %}
  &lt;/div&gt;
  </code></pre>
  
  <p>the problem is that el.content is different in size for any elements ad the resulting grid appears irregular.</p>