How to overlay an element?

[thiagosaadofficial]

I’m trying to override my image in the sub-header, so it overlaps the header and sub-header, getting on top of both and on top of the body, I’m using the following code according to W3, but it does not work As expected. How do I also make the h1 text to be on the side of the image but not overlapping?

.imgHeaders {
  width: 20%;
  position: absolute;;
  z-index: 4;
}

  <ion-navbar color='header-sub'>
    <ion-toolbar class='header-sub'>
      <img class='imgHeaders' src="../assets/img/imgRegister.png">
      <h1>Cadastro</h1>
    </ion-toolbar>
  </ion-navbar>
</ion-header>