title: Angular Primeng sidebar is transparent
body: <p>I'm currently on an Angular 7 project with PrimeNg v7.
  I want to use the PrimeNg sidebar module but I can't manage to remove the transparent background and the shadow does not appear when it's open :
  <a href="https://i.stack.imgur.com/CINHx.png" rel="nofollow noreferrer">What I get</a></p>
  
  <p>I want it to be just like on the primeNg website :
  <a href="https://i.stack.imgur.com/ympDV.png" rel="nofollow noreferrer">What I want</a></p>
  
  <p>Here is my code : appcomponent.html</p>
  
  <pre><code>&lt;!--The content below is only a placeholder and can be replaced.--&gt;
  &lt;p-sidebar [(visible)]="display" [baseZIndex]="10000"&gt;
      &lt;app-sidebar&gt;&lt;/app-sidebar&gt;
  &lt;/p-sidebar&gt;
  
  &lt;button type="text" (click)="display = true" pButton icon="pi pi-plus" label="Show"&gt;&lt;/button&gt;
  &lt;router-outlet&gt;&lt;/router-outlet&gt;
  </code></pre>
  
  <p>app.module.ts :</p>
  
  <pre><code>@NgModule({
    declarations: [
      AppComponent,
      SidebarComponent
    ],
    imports: [
      BrowserModule,
      BrowserAnimationsModule,
      AppRoutingModule,
      SidebarModule,
      ButtonModule,
      NgbModule
    ],
    providers: [{provide: 'pronosticServiceType', useClass: environment.pronosticServiceType}],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  
  <p>sidebar.component.html :</p>
  
  <pre><code>&lt;div&gt;
    &lt;div&gt;
      &lt;a href="/home"&gt;Home&lt;/a&gt;
    &lt;/div&gt;
    &lt;div&gt;
      &lt;a href="/Pronostics"&gt;Pronostics&lt;/a&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>