title: Can you change Angular mat-expansion-panel text/font colors?
body: <p>I cannot change the text color in the mat-expansion-panel?</p>
  
  <p>I've got an app with a mat-expansion-panel. I can change the background colors, etc, using .mat-expansion-panel-header, but nothing i do seems to affect the text color of the title. Trying to go from the default color white background black text, to a dark blue background (which i can do) and white text (which i cannot). </p>
  
  <p>I've tried varieties of options with -label, -text, and -typography, etc and no change.</p>
  
  <pre><code>/deep/ .mat-expansion-panel-header-label,
  .mat-expansion-panel-header-label.mat-expanded,
  .mat-expansion-panel-header-label.mat-expanded:hover {
    background: white;  
  
  }
  </code></pre>
  
  <p>I've tried numerous versions of things as shown above but get nothing. The basic expectation is the text comes out white instead of black.</p>