title: Angular Material table header sticky:true not working
body: <p>I have a Angular Material table within a div that has a max-height set and overflow-y: auto, but the headers are not sticking to the top of the viewport as expected.</p>
  <pre><code>    &lt;mat-table class=&quot;table&quot; mat-table [dataSource]=&quot;dataSource&quot; matSort&gt;
      ...
        &lt;tr mat-header-row *matHeaderRowDef=&quot;displayColumns; sticky: true&quot;&gt;&lt;/tr&gt;
        &lt;tr
          mat-row
          *matRowDef=&quot;
            let rateMethod;
            let j = index;
            columns: displayColumns
          &quot;
          (dblclick)=&quot;editRateMethod(rateMethod.rateMethodId)&quot;
          (contextmenu)=&quot;onContextMenu($event, rateMethod)&quot;
          [ngClass]=&quot;{ 'striped-row': j % 2 === 0 }&quot;
        &gt;&lt;/tr&gt;
      &lt;/mat-table&gt;
  </code></pre>