title: Angular Router Navigation doesnt remove previous component css
body: <p>I am new to angular and build two component in my first angular app.
  In first component i put a click on button to navigate to second component. </p>
  
  <p>I m using below code for navigation :</p>
  
  <pre><code>this.router.navigate(['../secondcomponent/'], { relativeTo: this.route });
  </code></pre>
  
  <p>but i can see that second component is having css of component 1. How can i make sure that on each router navigation previous component css will removed and only that component as well as the index.html css should be present?</p>