email input should be red like other input but is doesnt

Question

the input email like firs name and last name is invalid but the color on CSS dent match. I don't know what is a difference between this tow I change type of email to text but no direness the email input should be invalid but it doesn't

  ngOnInit(){
    this.reactiveForm=new FormGroup({
      firstname:new FormControl(null,Validators.required),
      lastname:new FormControl(null,Validators.required),
      email:new FormControl(null,[Validators.required]),
      country:new FormControl("iran"),
      gender:new FormControl("other"),
      hobbies:new FormControl(null),
    });
  }

Answer 1

That's not a lot of information to go on, but you could try changing

email:new FormControl(null,[Validators.required]),

to

email:new FormControl(null,Validators.required),

Answer 2

To validate an email add the Validators.email validator

{
    // other controls
    email:new FormControl(null, [Validators.required, Validators.email])
}

Also Angular adds the ng-invalid class to an input when invalid. If you have it, it's a css issue.