title: Angular mat-button style is not apllied in mat-dialog
body: <p>I have a project Angular 9. All works fine, but when mat-dialog is opened it contains a couple of buttons. And material-style is not applied to these buttons. I wonder why. The problem exists only an mat-dialog window. In other pages all works fine: mat-button style is applied correctly. Couldn't you help me with this issue?</p>
  <p><strong>Code enrollments.component.ts:</strong></p>
  <pre><code>import { Component, OnInit } from '@angular/core';
  import { DataService } from '../data.service';
  import { Enrollment } from './enrollment';
  import { MatDialog, MAT_DIALOG_DATA } from '@angular/material/dialog';
  
  @Component({
    selector: 'app-dialog-printdocs',
    templateUrl: './dialogprintdocs.component.html'
  })
  export class DialogPrintDocsComponent { }
  
  @Component({
    selector: 'app-enrollments',
    templateUrl: './enrollments.component.html',
    styleUrls: ['./enrollments.component.css']
  })
  export class EnrollmentsComponent implements OnInit {
  
    public enrollments: Enrollment[];
    public displayedColumns: string[] = ['id', 'date', 'freb', 'print'];
  
    constructor(
      private dataService: DataService,
      private dialog: MatDialog) { }
  
    ngOnInit(): void {
      this.loadData();
    }
  
    loadData(filter: string = null): void {
      this.dataService.getData(filter).subscribe(result =&gt; {
        this.enrollments = result;
      }, error =&gt; console.error(error));
    }
  
    openDialog() {
      this.dialog.open(DialogPrintDocsComponent);
    }
  }
  </code></pre>
  <p><strong>Code dialogprintdocs.component.html:</strong></p>
  <pre><code>&lt;button mat-button&gt;Cancel&lt;/button&gt;
  &lt;button mat-button&gt;OK&lt;/button&gt;
  </code></pre>
  <p><strong>Code app.module.ts:</strong></p>
  <pre><code>import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { FormsModule } from '@angular/forms';
  import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
  import { RouterModule } from '@angular/router';
  
  import { AppComponent } from './app.component';
  import { NavMenuComponent } from './nav-menu/nav-menu.component';
  import { EnrollmentsComponent } from './enrollments/enrollments.component';
  import { MaterialModule } from './material.module';
  import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
  
  @NgModule({
    declarations: [
      AppComponent,
      NavMenuComponent,
      EnrollmentsComponent
    ],
    imports: [
      BrowserModule.withServerTransition({ appId: 'ng-cli-universal' }),
      HttpClientModule,
      FormsModule,
      RouterModule.forRoot([
        { path: '', component: EnrollmentsComponent, pathMatch: 'full' },
      ]),
      MaterialModule,
      BrowserAnimationsModule
    ],
    providers: [],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  <p><strong>Code material.module.ts:</strong></p>
  <pre><code>import { NgModule } from '@angular/core';
  import { MatTableModule } from '@angular/material/table';
  import { MatInputModule } from '@angular/material/input';
  import { MatIconModule } from '@angular/material/icon';
  import { MatDialogModule } from '@angular/material/dialog';
  import { MatButtonModule } from '@angular/material/button';
  
  @NgModule({
      exports: [
          MatTableModule,
          MatInputModule,
          MatIconModule,
          MatDialogModule,
          MatButtonModule
      ]
  })
  export class MaterialModule { }
  </code></pre>