title: How to change mat-checkbox background-color in CSS3 ? Angular6
body: <p>I need change background with mat-ripple use class="matCheckboxClass"</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;mat-checkbox class="matCheckboxClass"&gt;&lt;/mat-checkbox&gt;
  </code></pre>
  
  <p>CSS3:</p>
  
  <pre><code>.matCheckboxClass .mat-checkbox-checked
  .mat-accent.mat-checkbox-background, .mat-checkbox-indeterminate.mat-accent 
  .mat-checkbox-background {
  background-color: rgb(27, 142, 241) !important;
  }
  
  .matCheckboxClass .mat-ripple-element  {
   background: rgba(27, 142, 241, .4) !important;
   }
  </code></pre>
  
  <p><strong>Note: ::ng-deep will change all mat-checkbox I need change specific mat-checkbox.</strong></p>