title: Angular material change outline appearance of form field
body: <p>Hi from this question <a href="https://stackoverflow.com/questions/51096529/changing-border-color-in-mat-form-field">Changing border color in mat-form-field</a> I already learned how to change the caret-color of a mat-form-field in case of invalid input, but I can't figure out how to change the outline color of such. </p>
  
  <p>caret example</p>
  
  <pre><code>.mat-form-field-invalid .mat-input-element, .mat-warn .mat-input-element {
  caret-color: #fbc1c1; 
  } 
  </code></pre>
  
  <p>what I thought would work:</p>
  
  <pre><code>.mat-form-field-invalid .mat-form-field-outline, .mat-warn .mat-form-field-outline{
  color: #fbc1c1;
  }
  </code></pre>