title: mat-typography CSS class is not working
body: <p>I'm following t<a href="https://material.angular.io/guide/typography" rel="nofollow noreferrer">his guide</a> to use fonts with angular material.
  the problem is element classes such as:</p>
  
  <pre><code>&lt;a href="#" class="mat-button"&gt;somthing&lt;/a&gt;
  </code></pre>
  
  <p>is working, while mat-typography global class is not:</p>
  
  <pre><code>&lt;body class="mat-typography"&gt;  
   &lt;app-root&gt;&lt;/app-root&gt; 
  &lt;/body&gt;
  </code></pre>
  
  <p>styles.css:</p>
  
  <pre><code>/* You can add global styles to this file, and also import other style files */
  @import "~@angular/material/prebuilt-themes/indigo-pink.css";
  @import "https://fonts.googleapis.com/css?family=Roboto:300,400,500";
  @import "https://fonts.googleapis.com/icon?family=Material+Icons";
  </code></pre>
  
  <p>where is the mistake?</p>