在angular-bootstrap-calendar中保留选定日期的背景色

import { Component } from '@angular/core';
import { CalendarEvent, CalendarMonthViewDay } from 'angular-bootstrap-calendar';

@Component({
  selector: 'app-my-component',
  template: `
    <mwl-calendar-month-view
      [viewDate]="viewDate"
      [events]="events"
      [activeDayIsOpen]="true"
      (dayClicked)="dayClicked($event.day)">
    </mwl-calendar-month-view>
  `
})
export class MyComponent {
  viewDate: Date = new Date();
  events: CalendarEvent[] = [
    {
      start: new Date(), // 事件开始日期
      title: '选定日期', // 事件标题
      color: { // 事件背景色
        primary: '#ad2121',
        secondary: '#FAE3E3'
      }
    }
  ];

  dayClicked(day: CalendarMonthViewDay): void {
    // 处理日期点击事件
    console.log(day);
  }
}