title: Angular: Material custom theme doesnt apply in input field
body: <p>I have the following material custom sass file:</p>
  
  <pre><code>@import '../node_modules/@angular/material/theming';
  @include mat-core();
  
  $app-primary: mat-palette($mat-red, 700, 800);
  $app-accent: mat-palette($mat-red, 700, 800);
  $app-warn: mat-palette($mat-red, 700, 800);
  $app-theme: mat-light-theme($app-primary, $app-accent, $app-warn);
  
  $app-input-primary: mat-palette($mat-red, 100, 200);
  $app-input-accent: mat-palette($mat-red, 100, 200);
  $app-input: mat-light-theme($app-input-primary, $app-input-accent);
  
  
  @include mat-core-theme($app-theme);
  @include mat-checkbox-theme($app-theme);
  @include mat-radio-theme($app-theme);
  @include mat-input-theme($app-theme);
  </code></pre>
  
  <p>The styles apply correctly to the checkbox and the radiobox, but do not apply in the input fields.</p>
  
  <p>This is how I define the input field:</p>
  
  <pre><code>&lt;md-form-field&gt;
      &lt;input mdInput placeholder="Card holder name"&gt;
  &lt;/md-form-field&gt;
  </code></pre>
  
  <p>The image below shows that the red style is applied to the radio, but the input loses the styles
  <a href="https://i.stack.imgur.com/CpdG1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/CpdG1.png" alt=""></a></p>
  
  <p>If I change the broken-down includes with the one-liner <code>@include angular-material-theme($app-theme);</code> the red style works on the input, but my idea is to have a different palette for the input fields.</p>