.header-image {
  position: fixed;
  top: 0;
  z-index: -1;
  height: 30rem;
  width: 100%;
}
/* fade into body background-color */
.header-image::after {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: -webkit-linear-gradient(bottom, #efefef, transparent 75%);
  background: linear-gradient(to top, #efefef, transparent 75%);
}
/* img set with WordPress Customizer */
.header-image img {
  width: 100%;
  height: 100%;
  -o-object-fit: cover;
     object-fit: cover;
}