Typescript Angular 4 Material matbutton按钮样式未应用于matdialog组件

我想创建一个mat-dialog，默认样式为mat-button，用于关闭对话框.除了按钮缺少棱角material 应用的material 设计风格外，其他一切都可以正常工作.

我该如何展现自己的风格？我已经按要求导入了所有模块，共properly set up each part of Angular Material including the themes个.

my-dialog.component.ts:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-my-dialog',
  templateUrl: './my-dialog.component.html',
  styleUrls: ['./my-dialog.component.css']
})
export class MyDialogComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

}

my-dialog.component.html:

<h1 mat-dialog-title>Lorem Ipsum</h1>
<div mat-dialog-content>
  ...
</div>
<button mat-button mat-dialog-close>Close</button>

app.module.ts:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MatCardModule, MatDialogModule, MatButtonModule } from '@angular/material'

import { AppComponent } from './app.component';
import { MyDialogComponent } from './my-dialog/my-dialog.component';

@NgModule({
  declarations: [
    AppComponent,
    MyDialogComponent
  ],
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    MatCardModule,
    MatDialogModule 
  ],
  providers: [],
  bootstrap: [AppComponent],
  entryComponents: [
    MyDialogComponent
  ]
})
export class AppModule { }