如何在Ionic4中增加警报组件的宽度？

.custom-alert {
  max-width: 400px; /* 设置最大宽度 */
  width: 80%; /* 设置宽度百分比 */
}

import { AlertController } from '@ionic/angular';

constructor(private alertController: AlertController) {}

async presentAlert() {
  const alert = await this.alertController.create({
    cssClass: 'custom-alert', // 添加自定义CSS类
    header: 'Alert',
    message: 'This is an alert message.',
    buttons: ['OK']
  });

  await alert.present();
}