app.component.html

<div id="top-container">
    <div id="left-menu">
      <router-outlet name="left-menu"></router-outlet>
    </div>
  
    <div id="contentarea">
      <div id="topbar">
        <top-menu></top-menu>
      </div>
      <div id="content">
        <router-outlet></router-outlet>
      </div>
    </div>
  </div>