Sizing of my application is not responsive

Ionic Framework ionic-v3
4

or you can try to organize all of your contents using <ion-grid> to put them in a specific row & place on your screen.

<ion-grid>
  <ion-row>
    <ion-col col-3> </ion-col> 
   <ion-col col-3></ion-col>
 <ion-col col-3> </ion-col> 
  <ion-col col-3></ion-col>
  </ion-row>
 </ion-grid>