title: Angular 6 theming : How do i set background color and use in entire app
body: <p>I have theme.scss file in which i have set the colors  like below :</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>/* mat-palette accepts $palette-name, main, lighter and darker variants */
  
  @import '~@angular/material/theming';
  @include mat-core();
  
  $gims-app-primary: mat-palette($mat-blue,500,900,A100);
  $gims-app-accent:  mat-palette($mat-yellow, 500, A200, A100);
  $gims-app-warn:    mat-palette($mat-red,500,900,A100);
  
  $gims-app-theme: mat-light-theme($gims-app-primary, $gims-app-accent, $gims-app-warn);
  
  @include angular-material-theme($gims-app-theme);</code></pre>
  </div>
  </div>
  </p>
  
  <p>I need to declare a background color here and use it in entire app.
  Since i will be implementing light and dark theme , the background color should be configurable. 
  Any idea how to achieve it ? </p>