Background image and color not work in NATIVE APP ANDROID

Background does not work in native emulator or ionic (Image01).

working only when run in the browser (Image02).

.welcome-card ion-img {
    max-height: 35vh;
    overflow: hidden;
  :host {
    .background-image {
      --background: url("../../assets/img/bg.jpg") no-repeat center center / 100% 100% !important;
  } ...

The same happens with the background of the buttons elements.

    --background: transparent;  
   --box-shadow: 0;
    color: transparent;
    height: 9em;
    margin-top: 0em;
    margin-bottom: 4em;
    --background-focused: transparent !important;
    --background-activated: transparent;

Already try to correct the problem by adding --ion-- at the beginning of the code, but I did not succeed.

Please, help me!