title: Styling Material grid-list items
body: <p>So this:</p>
  
  <pre><code>   &lt;md-grid-list cols="5" rowHeight="20px"&gt;
        &lt;md-grid-tile
            *ngFor="let carBrand of carBrands"
            colspan= 1
            rowspan= 1&gt;
          &lt;md-checkbox&gt;{{ carBrand}}&lt;/md-checkbox&gt;
        &lt;/md-grid-tile&gt;
      &lt;/md-grid-list&gt;
  </code></pre>
  
  <p>generates my list, but all items in cols are centered. I see in dev tools that if I change <code>justify-content: center</code> to <code>justify-content: left</code> it probably works well, but can not achieve same effect in my code. </p>
  
  <p>How to properly style these?  </p>