title: Apply css style to all components in Angular 2 app
body: <p>I have very basic, and reusable css rules, such as:</p>
  
  <pre><code>.ng-invalid {
      border-left: 5px solid #a94442;
  }
  
  .ng-valid {
      border-left: 5px solid #42A948;
  }
  </code></pre>
  
  <p>I'd like to re-use these for all of my components. If I place this in my root <code>AppComponent</code>, which is the one that is bootstrapped by Angular, then it's not recognized by any other components in my application other than the <code>AppComponent</code>.</p>
  
  <p>I must be missing something very obvious here.</p>