title: Angular Material2 theming - how to set app background?
body: <p>I am building an angular2 app using angular material2. I am trying to set the background of my application "the correct way", but I can't figure out how.</p>
  
  <p>I found a class I can use on my <code>&lt;body&gt;</code> element: <code>mat-app-background</code> which I can add, that gives me a default color (depending on whether I'm using the light or dark themes).</p>
  
  <p>I wish to define this background color to use my brands' color, but I cannot figure out how to do it.</p>
  
  <p>In <code>_theming.scss</code> it is defined like so:</p>
  
  <pre><code>// Mixin that renders all of the core styles that depend on the theme.
  @mixin mat-core-theme($theme) {
    @include mat-ripple-theme($theme);
    @include mat-option-theme($theme);
    @include mat-pseudo-checkbox-theme($theme);
  
    // Wrapper element that provides the theme background when the
    // user's content isn't inside of a `md-sidenav-container`.
    .mat-app-background {
      $background: map-get($theme, background);
      background-color: mat-color($background, background);
    }
    ...
  }
  </code></pre>
  
  <p>So I thought it would make sense to try adding the background color to my custom theme, somehow, but I couldn't understand how to do so.</p>
  
  <p>On the Material2 <a href="https://github.com/angular/material2/blob/master/guides/theming.md" rel="noreferrer">theming</a> documentation it only says:</p>
  
  <p>"In Angular Material, a theme is created by composing multiple palettes. In particular, a theme consists of:</p>
  
  <ul>
  <li>A primary palette: colors most widely used across all screens and components.</li>
  <li>An accent palette: colors used for the floating action button and interactive elements.</li>
  <li>A warn palette: colors used to convey error state. </li>
  <li>A foreground palette: colors for text and icons.</li>
  <li>A background palette: colors used for element backgrounds.
  "</li>
  </ul>
  
  <p>How can I add my background to the theme, or do it in any other way?</p>