title: can't change angular's material select placeholder color
body: <p>im having problem with setting placeholder's color to white on the dark background, when setting to white, it has weird stroke like this:
  <a href="https://i.stack.imgur.com/byw6i.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/byw6i.png" alt="enter image description here"></a></p>
  
  <p><a href="https://stackblitz.com/edit/angular-twbzew-ealbnk" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-twbzew-ealbnk</a></p>
  
  <pre><code>&lt;mat-form-field&gt;
      &lt;mat-select [ngClass]="className" placeholder="{{someText}}"&gt;
          &lt;mat-option *ngFor="let item of items" [value]="item.value"&gt;
              {{ item.viewValue }}
          &lt;/mat-option&gt;
      &lt;/mat-select&gt;
  &lt;/mat-form-field&gt;
  
  
  .basic-container {
      background: black;
  
    padding: 5px;
  }
  
  
  .class1  .mat-select-placeholder {
    color:white !important;
  }
  </code></pre>