title: Add background color to a specific date
body: <p>I have a calendar and using material-calendar , I just want to highlight a specific date eg 19-7-2018,  meaning it should have a background color eg red</p>
  
  <p>Here is what I have done so far</p>
  
  <pre><code>&lt;div class="form-group form-element_date"&gt;
            &lt;mat-calendar  [minDate]="minimumDate" [maxDate]="restrictedBookingDates" mat-date-filter="restrictedBookingDates"  [selected]="selectedDate" (selectedChange)="selectedDate = $event"&gt;
              &lt;ng-template pTemplate="date" let-date&gt;
                &lt;span  class="dot" [ngStyle]="{backgroundColor: (date.day ==19) ? '#348db2' : 'inherit'}"   
                &gt;{{date.day}}&lt;/span&gt;
            &lt;/ng-template&gt;
            &lt;/mat-calendar&gt;
          &lt;/div&gt;
  </code></pre>
  
  <p>Unfortunately this does not work </p>
  
  <p>What is wrong with my code? </p>