材料2 sidenav不加载css文件

Question

我正在使用角度cli和角度材料2.按钮工具栏可以获得正确的设计颜色，但是当我想实现sidenav时，按钮单击将添加.mdsidenav-opening类，但没有css规则。

<md-sidenav-layout fullscreen>
 <md-sidenav #sidenav>
    <md-nav-list *shellNoRender>
      <a md-list-item *ngFor="let view of views">
        <md-icon md-list-icon>{{view.icon}}</md-icon>
        <span md-line>{{view.name}}</span>
        <span md-line>{{view.description}}</span>
      </a>
    </md-nav-list>
  </md-sidenav>
  <md-toolbar color="primary">
    <button md-icon-button (click)="sidenav.toggle()">
      <md-icon>menu</md-icon>
    </button>
    Puppy Love
  </md-toolbar>
  <router-outlet *shellNoRender></router-outlet>
</md-sidenav-layout>