.wp-block-cover.is-style-gradient-background {
  position: relative;
  overflow: hidden;
}

.wp-block-cover.is-style-gradient-background > .wp-block-cover__background,
.wp-block-cover.is-style-gradient-background > .wp-block-cover__image-background {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.wp-block-cover.is-style-gradient-background::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url("../assets/images/test.png") center bottom / cover no-repeat;
  z-index: 1;           
  opacity: 1;           
  pointer-events: none;
}

.wp-block-cover.is-style-gradient-background > .wp-block-cover__inner-container {
  position: relative;
  z-index: 2;
}