title: Angular Material theme issue
body: <p>I am using angular material in my project. I have used side navbar and stepper, but they are not looking as they look in demo.
  I have imported required CSS theme in scss file.
  Please find below codes,</p>
  
  <p>formstepper.component.html</p>
  
  <pre><code>&lt;button mat-raised-button (click)="isLinear = !isLinear" id="toggle-linear"&gt;
      {{!isLinear ? 'Enable linear mode' : 'Disable linear mode'}}
    &lt;/button&gt;
    &lt;mat-horizontal-stepper [linear]="isLinear" #stepper&gt;
      &lt;mat-step [stepControl]="firstFormGroup"&gt;
        &lt;form [formGroup]="firstFormGroup"&gt;
          &lt;ng-template matStepLabel&gt;Fill out your name&lt;/ng-template&gt;
          &lt;mat-form-field&gt;
            &lt;input matInput placeholder="Last name, First name" formControlName="firstCtrl" required&gt;
          &lt;/mat-form-field&gt;
          &lt;div&gt; 
            &lt;button mat-button matStepperNext&gt;Next&lt;/button&gt;
          &lt;/div&gt;
        &lt;/form&gt;
      &lt;/mat-step&gt;
      &lt;mat-step [stepControl]="secondFormGroup"&gt;
        &lt;form [formGroup]="secondFormGroup"&gt;
          &lt;ng-template matStepLabel&gt;Fill out your address&lt;/ng-template&gt;
          &lt;mat-form-field&gt;
            &lt;input matInput placeholder="Address" formControlName="secondCtrl" required&gt;
          &lt;/mat-form-field&gt;
          &lt;div&gt;
            &lt;button mat-button matStepperPrevious&gt;Back&lt;/button&gt;
            &lt;button mat-button matStepperNext&gt;Next&lt;/button&gt;
          &lt;/div&gt;
        &lt;/form&gt;
      &lt;/mat-step&gt;
      &lt;mat-step&gt;
        &lt;ng-template matStepLabel&gt;Done&lt;/ng-template&gt;
        You are now done.
        &lt;div&gt;
          &lt;button mat-button matStepperPrevious&gt;Back&lt;/button&gt;
          &lt;button mat-button (click)="stepper.reset()"&gt;Reset&lt;/button&gt;
        &lt;/div&gt;
      &lt;/mat-step&gt;
    &lt;/mat-horizontal-stepper&gt;
  </code></pre>
  
  <p>formstepper.component.scss</p>
  
  <pre><code>@import "../../../node_modules/@angular/material/prebuilt-themes/deeppurple-amber.css";
  </code></pre>
  
  <p>formstepper.component.ts</p>
  
  <pre><code>import {Component, OnInit} from '@angular/core';
  import {FormBuilder, FormGroup, Validators} from '@angular/forms';
  
  /**
   * @title Stepper overview
   */
  @Component({
    selector: 'FormstepperComponent',
    templateUrl: './formstepper.component.html',
    styleUrls: ['./formstepper.component.scss'],
  })
  export class FormstepperComponent implements OnInit {
    isLinear = false;
    firstFormGroup: FormGroup;
    secondFormGroup: FormGroup;
  
    constructor(private _formBuilder: FormBuilder) {}
  
    ngOnInit() {
      this.firstFormGroup = this._formBuilder.group({
        firstCtrl: ['', Validators.required]
      });
      this.secondFormGroup = this._formBuilder.group({
        secondCtrl: ['', Validators.required]
      });
    }
  }
  </code></pre>
  
  <p>App.module.ts</p>
  
  <pre><code>import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { AppRoutingModule } from './app-routing.module';
  import { AppComponent } from './app.component';
  import { MyNavComponent } from './my-nav/my-nav.component';
  import { LayoutModule } from '@angular/cdk/layout';
  import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
  import { MatToolbarModule, MatButtonModule, MatSidenavModule, MatIconModule, MatListModule, MatStepperModule
          ,MatFormFieldModule, MatInputModule } from '@angular/material';
  import { FormstepperComponent } from './formstepper/formstepper.component';
  import { FormsModule, ReactiveFormsModule } from '@angular/forms';
  import 'hammerjs';
  
  @NgModule({
    declarations: [
      AppComponent,
      MyNavComponent,
      FormstepperComponent,
    ],
    imports: [
      BrowserModule,
      AppRoutingModule,
      LayoutModule,
      MatToolbarModule,
      MatButtonModule,
      MatSidenavModule,
      MatIconModule,
      MatListModule,
      MatStepperModule,
      MatFormFieldModule,
      MatInputModule,
      FormsModule,
      ReactiveFormsModule,
      BrowserAnimationsModule
    ],
    exports: [
      BrowserModule,
      AppRoutingModule,
      LayoutModule,
      MatToolbarModule,
      MatButtonModule,
      MatSidenavModule,
      MatIconModule,
      MatListModule,
      MatStepperModule,
      MatFormFieldModule,
      MatInputModule,
      FormsModule,
      ReactiveFormsModule,
      BrowserAnimationsModule
    ],
    providers: [],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  
  <p>Sidenavbar and stepper are displaying at browser but there styles are missing. They are very basic components.
  What I am missing here?</p>