place the icon to the leftmost of the toolbar

Ionic Framework
1

i am new to ionic. i want to place icon to the left most of the toolbar.
I have used slot="start" , class="float-right" and ion-float-right inside the tag but nothing works.

<ion-header>
  <ion-toolbar>
    
    <img  class="logo float-left"  src='../assets/dqlogo-edge.png'></img> 
    <ion-button class="grad-blue-button" size="large" slot="end">Login</ion-button> 
  </ion-toolbar>
</ion-header>

<ion-content>

</ion-content>


.logo{
    width:100%;
    height: 57px;
    float:  left !important;
}