title: how to set the width of angular material expand panel to fit the grid tile
body: <p>I'd like to use Material's GridList component to make two column layout. Inside I've placed ExpandPanels, but they are centered in the tile. I need them to fit the  horizontal space. Of course I could place a class attribute to the component and set the width, but I'm not sure if this is the best "material" way, to do this.
  Here my test example:</p>
  
  <pre><code>&lt;mat-grid-list cols="2" ratio="2:1"&gt;
    &lt;mat-grid-tile&gt;
      &lt;mat-expansion-panel [expanded]='true' &gt;
        &lt;mat-expansion-panel-header&gt;
          &lt;mat-panel-title&gt;
            TITLE
          &lt;/mat-panel-title&gt;
         &lt;/mat-expansion-panel-header&gt;
         &lt;mat-form-field&gt;
           &lt;input matInput placeholder="TEST"&gt;
         &lt;/mat-form-field&gt;
      &lt;/mat-expansion-panel&gt;
    &lt;/mat-grid-tile&gt;
    &lt;mat-grid-tile&gt;
      &lt;mat-expansion-panel [expanded]='true'&gt;
        &lt;mat-expansion-panel-header&gt;
          &lt;mat-panel-title&gt;
            TITLE2
          &lt;/mat-panel-title&gt;
        &lt;/mat-expansion-panel-header&gt;
        &lt;mat-form-field&gt;
          &lt;input matInput placeholder="TEST"&gt;
        &lt;/mat-form-field&gt;
      &lt;/mat-expansion-panel&gt;
    &lt;/mat-grid-tile&gt;
  &lt;/mat-grid-list&gt;
  </code></pre>
  
  <p>I'm quite new to angular and material. I would be happy about some suggestions.</p>