Ion-input lines on the sides when leaving focus

Ionic Framework ionic-v3
1

hi, I am facing a problem which is strange actually…

image

lines appear on the sides of the input when leaving focus… and this only happens when changing to certain mobiles/screen size

this .html side:

      <ion-item>
        <ion-label stacked>First Name</ion-label>
        <ion-input type="text" value="" clearInput mode="ios" formControlName="firstname"></ion-input>         
    </ion-item><br/>
    <div class="error-box" *ngIf="firstname.invalid && firstname.errors.required && firstname.touched">* First Name is required!</div>
	<div class="error-box" *ngIf="firstname.invalid && firstname.errors.maxlength">* Maximum name length is 15!</div>
	<div class="error-box" *ngIf="firstname.invalid && firstname.errors.pattern">* First Name cannot contain numbers or special characters!</div>